The physicians on Forbes' 38th World's Billionaires list are among the richest in the world.
Here is how five of these physicians made their fortunes:
Thomas Frist Jr., MD, and family
Dr. Frist, a former Air Force flight surgeon, founded Nashville, Tenn.-based HCA Healthcare with his father in 1968. Today, he owns more than 20% of the company with his family.
Patrick Soon-Shiong, MD
Dr. Soon-Shiong invented the cancer drug Abraxane. In 2010 and 2008 respectively, he sold his drug companies Abraxis and American Pharmaceutical Partners for a combined $9.1 billion.
Leonard Schleifer, MD, PhD
Dr. Schleifer cofounded drugmaker Regeneron in 1988. He is currently the CEO of the company.
August Troendle, MD
Dr. Troendle is the CEO of Medpace, a clinical research company that he founded. Prior to starting Medpace, Dr. Troendle served for five years as a director at Swiss pharmaceutical company Sandoz, now known as Novartis.
George Yancopoulos, MD, PhD
Dr. Yancopoulos is the chief scientific officer of Regeneron. He joined the company one year after it was founded.