The birth of Mayo Clinic Laboratories: From tiny hometown operation to international mainstay


As the 1960s rolled into 1970, the country was in a recession and the Vietnam War showed no signs of ending. Rock icons Janis Joplin and Jimi Hendrix both died that year. Gross Domestic Product fell while inflation rose. Plus, interest rates soared to help pay for deficit spending on the war. Meanwhile, Mayo Clinic’s Board of Governors was considering new ways to bring in revenue.

So on March 17, 1971, after much investigation, hesitation, and deliberation, the Regional Laboratory was founded. For the first time in Mayo Clinic’s history, the institution would get involved with the community practice of pathology to serve outside patients in the region and beyond. Before this, Mayo was entirely an academic institution, serving only its own patients. The funds from this new lab would be used for research and education.

The visionary of this venture was Michael O’Sullivan, M.D., who was appointed the lab’s first medical director by his mentor, Charles Owen, M.D., a board member and chair of the Department of Clinical Laboratories. “I was dumbfounded when he asked me to be director of this new operation,” says Dr. O’Sullivan. “I told him, ‘Chuck, you’re making a big mistake. I’ve only been on staff for a year. There are plenty of others with better reputations than me.’” But given his mentor’s insistence, Dr. O’Sullivan eventually relented.

Michael O'Sullivan, M.D., 1980

When Irish eyes are smiling

The fact that the Regional Laboratory was founded on St. Patrick’s Day seems appropriate given that Dr. O’Sullivan is an Irish immigrant from Listowel, a little town in County Kerry. “I don’t think it was merely coincidence,” he says. “I think good ole St. Patrick was smiling down on us.”

The first Mayo Clinic building, now known as the “1914 Building,” was the original location of the Regional Laboratory

Dr. O’Sullivan’s righthand man in this endeavor was Gerald (Jerry) Wollner, who had been administrative assistant to the department before being appointed chief administrator (today, that title would be considered chief operations officer, while Dr. O’Sullivan’s title would be chief executive officer). The lab was initially located in the lower level of the 1914 Building. Shortly thereafter, the lab moved to a small area on the first floor of the Plummer Building. 

A two-pronged approach

Mind you, this critical venture didn’t just happen overnight. Wollner and Dr. O’Sullivan had to do a feasibility study and an enormous amount of field research before launching their plans.  

“We researched both a regional lab and a national reference lab concept,” says Wollner, who retired in 1997 after 35 years with Mayo. “We did that by visiting many more laboratories than the small group of board members initially did.” Wollner and Dr. O’Sullivan then recommended to the board that they start small and take it slow, and that they should pursue a two-pronged approach.     

Gerald Wollner, 1977

The first prong was to create a regional lab — for an area encompassing south of the Twin Cities and northern Iowa — that would cater to smaller hospitals in need of pathology services. “In our surveys, we found out there were four hospitals in this area that had no pathology coverage,” says Dr. O’Sullivan. “We wanted to focus our efforts on the region first, and to test our systems to see if everything was running smooth enough before we expanded.”

The expansion, or second prong, entailed the creation of a national reference lab, called Mayo Medical Laboratories, which meant developing the systems, forms, and transportation mechanisms so that both regional and more national clients — initially from cities like Chicago, Minneapolis, and Milwaukee — could send their specimens to Rochester.

This was no easy task, because Mayo also had to continue serving and treating its own patients. Further, there was no sales force or marketing department. So it fell on the two men to travel from hospital to hospital to court more pathology business.

Drumming up business

Wollner, who would co-found the Clinical Laboratory Management Association in 1976 (today, one of the leading associations of its kind) and become president of the Minnesota Medical Group Management Association in the mid-80s, had already built relationships with many leaders at smaller laboratories and group practices. So he made the phone calls to line up sales appointments. 

Wherever the two men went, Mayo’s reputation preceded them — thanks to renowned surgical pathologists such as Louis Weiland, M.D., and his predecessors who were “well known for over fifty years,” says Wollner. “Every single pathologist in this country, I believe, knew of Mayo’s surgical pathology because they had consulted with us for second opinions.” It also helped that Mayo had a clinical practice that was known for serving its patients “so intimately,” according to Dr. O’Sullivan.

Wollner and Dr. O’Sullivan were the first two people in Mayo’s history to be given an expense account for gas, hotels, and meals to support their sales calls.

Louis Weiland, M.D., 1972

Another first? They were given a company car for such trips. Before that, the men were using their own vehicles. “It took us a couple years to convince Mayo Clinic that we needed an official car that was always available when we had to go out and visit these clients — a car that only we could use,” says Wollner. “So around 1973, they bought us a four-door Plymouth.”

Most regional hospitals were delighted at this new opportunity to benefit from Mayo’s pathology services. As were pathologists who practiced alone in Minnesota cities like Austin, Albert Lea, Winona, and Red Wing, who agreed to send their reference lab work to Mayo. There were about seven pathologists altogether. “We invited these pathologists to Mayo on a monthly basis,” says Dr. O’Sullivan.

“We would have educational programs for them, and then discuss the issues they were confronting as practicing pathologists. And we would share our experiences with them. This was critically important to the development of our concepts.”

Dr. O’Sullivan

The little lab that could

The first specimens started coming to the Regional Laboratory in the spring of 1971.

“Focusing on the region first helped us get started on the reference program,” says Dr. O’Sullivan, who served in the U.S. Air Force during The Cuban Missile Crisis in 1962, before coming to Mayo in 1964 to finish his studies in pathology.

“Once we had the reference lab and were beginning to expand outside the region, the term ‘Regional Laboratory’ did not make sense anymore. So that’s when we changed the name to Mayo Medical Laboratories.”

To put into perspective how far the lab has come, consider these stats: Over its inaugural week, the lab received 25 test requests. By midsummer the lab had 14 clients. For the month of July, the lab performed 219 tests and earned $3,000 in revenue. By the end of its first year in 1971, the lab had 83 clients and had performed 1,600 tests, with a revenue of $26,000. It averaged 10 to 100 tests per day.

Today, Mayo Clinic Laboratories has more than 4,000 national and international clients and, in normal circumstances, averages about 35,000 tests per day. However, in November of 2020, a peak month for COVID-19 cases, there were instances when test volume nearly tripled to 100,000 per day.

Mayo Clinic Laboratories’ remarkable success would certainly allude to St. Patrick’s blessings over the last 50 years, not to mention all the good people who helped lay the foundation. Besides Dr. O’Sullivan and Wollner, they include Stephen Woo, M.D.; Dennis Leavelle, M.D.; Curtis Bakken, M.D.; Nancy Bill; Claudia Grassle; Sharon Dunemann; Paul Beyer; Patti Welch; Susan Towers; Jennifer Crawford, and so many others.   

“When I look back on it all,” says Dr. O’Sullivan, who retired in 2002 as CEO of Mayo Clinic’s Arizona campus, “I think, ‘My god, look at where we are today.”  


This article is part of our 50th anniversary series. Learn more about Mayo Clinic Laboratories’ history.

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Chris Bahnsen

Chris J. Bahnsen covers emerging research and discovery for Mayo Clinic Laboratories. His writing has also appeared in The New York Times, Los Angeles Times, and Smithsonian Air & Space. He divides his time between Southern California and Northwest Ohio.