My mission is to treat my patients with compassion and kindness and take the time to know and understand them.

I am certified by the American Board of Internal Medicine in Internal Medicine, Medical Oncology and Hematology. I received my BA in Biology at State University of New York at Buffalo and my MD from Jefferson Medical College of Thomas Jefferson University in Philadelphia, PA. I did my residency in Medicine at Lankenau Hospital in Philadelphia, PA and Fellowship in Hematology-Oncology at University of Connecticut Health Center in Farmington, CT. I was recognized in Boston Magazine's 2017 Top Doctors list. Outside of work, I enjoy listening to classical music, traveling, running, and bicycling. 

I strive to help patients attain the best health possible; have full understanding of their health issues; and equip them to take partnership in managing their health.

I enjoy helping people stay healthy through preventative medicine, as well as treating both developing and ongoing health issues. I especially value getting to know my patients over time.

My mission is to engage patients to participate in their medical management.

I enjoy establishing long-term relationships with my patients to enhance their participation in their plan of care.

William Tollefsen, MD is the EMS and MIH Medical Director for South Shore Health. Dual-boarded in Emergency Medicine and EMS Medicine, Dr. Tollefsen works clinically as an Emergency Physician at South Shore Health in addition to his role as EMS Medical Director.

One of few physicians in the country to receive the prestigious "FAEMS" recognition, Dr. Tollefsen is also the Medical Director for OEMS Region IV, serving 61 cities and towns of the Metro-Boston EMS Council. As the current EMS Medical Director for eight municipal and three private ambulance services on the South Shore, Dr. Tollefsen interacts and provides oversight for over 400 Paramedics.

Dr. Tollefsen graduated from New York Medical College and completed residency training in Emergency Medicine at Harvard University, Brigham and Women's, and Massachusetts General Hospital. He completed a fellowship in Emergency Medical Services and Critical Care Transport at the University of Massachusetts, where he worked as an Emergency Physician and Flight Physician for UMASS LifeFlight. He completed an MBA at the Isenberg School of Management at UMASS Amherst, and holds a Master of Medical Science degree from the Boston University School of Medicine.

A former pre-hospital provider, he is actively involved in EMS system design, paramedic education and Critical Care Transport Systems. He works closely with multiple EMS, Fire and Law Enforcement agencies throughout Massachusetts.

His research interests include systems of care, resuscitation, airway management, and paramedic education.

My treatment philosophy is to establish good rapport with patients during their difficult moments, and to focus on shared decision-making while working on treatment plans and management of acute issues.

I have been practicing medicine for more than 20 years now. I like communicating with patients while focusing on their medical issues and helping formulate plans to meet the treatment needs. Apart from medicine, I enjoy spending time with my two boys, cooking and baking. I am an avid nature lover and enjoy hiking. Exploring new places brings me true happiness. Yoga and meditation helps me unwind after hectic days.