While at Stanford he also did and NIH postdoctoral fellowship in heart and lung transplant pathology in the Laboratory of Dr. Margaret E. Billingham.
Tazelaar worked for 17 years at the Department of Pathology at the Mayo Clinic in Rochester, Minnesota and is currently a consultant at Mayo Clinic in Arizona and professor of Pathology, Mayo Clinic College of Medicine as well as being Vice Chair of Quality and Education in the Department of Laboratory Medicine and Pathology.
Currently, Dr. Tazelaar is Chairman of the Department of Laboratory Medicine and Pathology at Mayo Clinic Scottsdale.
He is nationally renowned as an expert in both these fields and lectures on a regular basis around the world.
[4] Tazelaar was part of the team that described pulmonary lymphangioleiomyomatosis (a disease that occurs almost exclusively in women) in a male patient.