Dr. Frederic E. Mohs Oral History Project


The University of Wisconsin Oral History Program–part of the UW-Madison Archives & Records Management–presents the incredible career and extraordinary life and work of Dr. Frederic E. Mohs, M.D. Developed at the University of Wisconsin-Madison in 1936, Mohs surgery is now practiced worldwide and has been proven to be one of the most effective procedures for treating skin cancer. The impact Dr. Frederic E. Mohs had on not only skin cancer treatment but dermatology as a discipline is universally profound, and the Oral History program is proud to recognize his influence through the collection of stories and memories, along with experiences, opinions and information regarding his work. Dr. Mohs was known for being extremely hard working, even-tempered and kind. This project has been undoubtedly special for those of us who have worked to collect the oral histories and honor his life’s work. To commemorate the success of Dr. Frederic E. Mohs, M.D., the oral history project was started in 2021, with the assistance of Dr. Juliet Aylward, M.D., Professor and Section Chief of Dermatologic Surgery at the University of Wisconsin School of Medicine and Public Health, to collect the oral histories and memories associated with Dr. Mohs and his legacy.

Dr. Frederic Edward Mohs, M.D. (1910-2002)

This is a black and white picture of Dr. Frederic Mohs. Mohs is dressed in a suit and tie.
Dr. Frederic Mohs. UW Archives Image S06369.

Dr. Frederic Edward Mohs, M.D., was born in Burlington, Wisconsin in 1910. He graduated from the University of Wisconsin and then from the University of Wisconsin School of Medicine and Public Health in 1934. As a UW graduate student and medical student, Dr. Mohs was the Brittingham Research Assistant to Professor Michael F. Guyer, a geneticist and the long-time head of the Zoology Department at the University of Wisconsin. During their first collaborative research project together, the pair became interested in comparing the leukocytic infiltration in cancerous and normal tissues of rats through the application of chemical irritants. From their research, Professor Guyer and Dr. Mohs observed that the leukocytic infiltrate that developed at the edge of the necrotic tissues of their rats was dense in normal tissues but non-existent in the cancer tissue. Additionally, one of the chemical irritants, zinc chloride, had the added benefit of preserving the tissue architecture while simultaneously killing it. From there, a keratolytic of dichloroacetic acid, synthesized by UW Chemistry Professor Louis Kahlenberg, was then used to make the skin permeable to the zinc chloride. 

After experimenting with the application of chemical irritants on cancerous rats throughout the early 1930s, Dr. Mohs then pioneered a similar technique for removing cancers from human skin called chemosurgery. At the suggestion of Dean William S. Middleton, Dr. Mohs began treating skin cancer patients in July of 1936 at the age of only 26 years old. It was at this time that he opened the first Mohs Micrographic Surgery clinic at the University of Wisconsin School of Medicine and Public Health. In 1941, he published his discovery in Cancer Research after a controversial rejection by the Proceedings of the Society for Experimental Biology and Medicine. In the years that followed, Dr. Mohs clinically demonstrated chemosurgery to be a highly effective procedure for removing skin cancers and keeping patients cancer-free for years after treatment. It was through the use of the microscopic control of the surgery along with sketching what was being seen in the microscope that contributed most greatly to the cure rate success of the microscopically oriented histographic procedure. As a result, microscopically controlled surgery became an accepted alternative or supplement to traditional irradiation and chemotherapy skin cancer treatments. Today, Dr. Mohs’ technique, otherwise known as microscopically controlled surgery, micrographic surgery, or Mohs Micrographic Surgery, is practiced worldwide and is still considered to be a highly documented clinical success with practical efficacy due to its irrefutable logic.

Dr. Mohs treated an estimated 30,000 to 40,000 cancer patients over the course of his career at the University of Wisconsin School of Medicine and Public Health. He specialized in the treatment of external cancers of the face (lip, cheek, nose, chin, eye, eyelid, ear, neck and scalp), extremities (arms, hands, fingers, legs, feet and toes), and genitals. Dr. Mohs consistently and repeatedly demonstrated cure rates above 99 percent for multiple types of skin cancer using his method of treatment. Additionally, he was recognized for his contribution and dedication to his life’s work, receiving awards such as the Lila Gruber Award for Cancer Research from the American Academy of Dermatology in 1977, the International Facial Plastic Surgery Award in 1979, the Frederic E. Mohs Award from the Skin Cancer Foundation in 1982, the Discovery Award of the Dermatology Foundation in 1995, and a Commendation from the Office of Governor of the State of Wisconsin in 1996, as well as honorary fellowships and memberships in multiple professional organizations such as the Skin Cancer Foundation, American Society for Mohs Histotechnology and the Philadelphia Society of Facial Plastic Surgeons.

Dr. Frederic E. Mohs is remembered by those who loved him and by those who worked closely beside him as being extremely hard working, intelligent, even-tempered and kind. One of his son’s, Fred Mohs, once described him as being a courageous man of science — strong, fearless and heroic.

The History of Mohs Surgery

Developed by Dr. Frederic E. Mohs during the 1930s, Mohs surgery, otherwise known as Mohs Micrographic Surgery, has been refined and practiced for more than eight decades. Today, it is considered the most effective technique for treating basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) — the two most common types of skin cancer.  

This is a doctor (Mohs) and two others apparently performing surgery on someone.
Frederic E. Mohs is pictured with clinic staff and patient, on whom he appears to be performing an examination or procedure. University Archives Image S06372

In the initial years of the Mohs procedure, Dr. Mohs removed tumors with a chemo surgical technique where thin layers of tissue were excised and pathologically examined after the application of a zinc chloride paste. Additionally, Dr. Mohs developed a unique technique of color-coding excised specimens and, from there, created a mapping process to accurately identify the location of remaining cancerous cells. Each stage of, what was then, the original procedure took exactly one day for the chemical paste to properly prepare the targeted tissue. As the process evolved, Dr. Mohs and fellow surgeons were able to refine the technique and can now excise the tumor, remove layers of tissue and examine the fresh tissue immediately. The chemo surgical technique originally developed by Dr. Mohs is no longer used. However, important to note is that the heart of the procedure — the color-coded mapping of excised specimens and their thorough microscopic examination — does still remain as the definitive part of Dr. Mohs’, Mohs micrographic surgical procedure. 

After treating thousands of patients using Mohs Micrographic Surgery and training hundreds of physicians in his method of treatment, Dr. Frederic E. Mohs retired in 1982. Dr. Mohs left his practice in the capable hands of two of his trainees, Dr. Paul O. Larson, M.D., and Dr. Stephen N. Snow, M.D. Today, the Mohs Micrographic Surgery clinic is part of the University of Wisconsin School of Medicine and Public Health. The clinic continues to use Dr. Mohs’ gold standard of skin cancer treatment, known as Mohs Micrographic Surgery, to treat its patients. 

Dr. Frederic E. Mohs was described as being proud to share his work and research with those who worked beside him, despite being a very humble man. He was known for his strong work ethic in the clinic, and those who worked beside him often spoke of the healthy and educational environment they experienced while being involved with the clinic.


Listed below are the narratives of each person interviewed for this project. Those interviewed include the family of Dr. Mohs and those who worked closely beside him.

Please note that included with each narrator’s name is their oral history number.

  • Mary Jane Ellickson (2129)
  • Rachel Caruso (2129)
  • Perry Robins (2120)*
  • Michael Hetzer (2124)
  • Paul Larson (2130)
  • Stephen Snow (2125)
  • Hugh Greenway (2153)
  • Richard Dortzbach (2152)
  • John Zitelli (2154)
  • George Hruza (2151)
  • Dan Mohs (2240)

* Oral history interview not publicly available. Note: As of now (July 2023), all these interviews, except Robins, can be accessed by contacting the University Archives. These interviews, however, will be put online soon.

Color photograph showing Dr. Mohs (in a blue suit) showing a film to an audience in a conference room.
Frederic E. Mohs at work, possibly setting up for a Friday conference. Photo from the collection of William T. Summerlain, MD. University Archives Image S06375

Project Summary

This project would not have happened without the generous support of the Dermatological Surgery Section at the University of Wisconsin School of Medicine and Public Health and the Mohs Family. The interviews were conducted, processed and transcribed by student workers Sophie Clark, Emma Helstrom and Kayla Bell and was overseen by Oral Historian Troy Reeves. Thanks, too, to the teams at Digital Library Services & the Shared Development Group, particularly Steven Dast & Karen Rattunde for putting these collections online. The content for this webpage was written & compiled by Kayla Bell.

Here are project reflections written by the students, Sophie, Emma, Kayla. Kayla also wrote a piece on her interview with Dan Mohs in the Found in the University Archives Tumblr.


Along with content from the oral histories, Kayla Bell reviewed the following resources to create this webpage: Skin Cancer Treatment Resources, History of Mohs Surgery, and a page on Mohs from UW’s Dermatology Surgery Section.