John D. Baxter was a world-renowned physician-scientist who spent his life studying endocrinology and developing new treatments for endocrine and metabolic diseases. He served as Chief of the Division of Endocrinology at UCSF from 1980-97 and Director of the Metabolic Research Unit from 1981-2000. An early pioneer in recombinant DNA technology, John’s laboratory was first to clone rat, human and bovine growth hormone and prolactin and to show that bacteria could produce functional human hormones. This work led to the commercial production of ‘biosynthetic’ human growth hormone that is now used worldwide to treat human growth disorders, and biosynthetic bovine growth hormone which is used throughout the world to improve milk production. His group published the crystal structure of the liganded thyroid hormone receptor (TR) in 1995, the first crystal structure of a small molecule bound to a receptor. This structure permitted novel, rational drug design, and improved our understanding of ligand-induced conformational changes in the nuclear receptor. In collaboration with Tom Scanlan, he developed TR modulators that selectively target atherosclerosis, serum lipids, obesity and fatty liver. These and related compounds are presently in clinical trials. John was a member of The Institute of Medicine and The National Academy of Sciences and was an active member of the Endocrine Society, serving as President in 2002 and receiving its highest honor, the Koch Award, in 2007. He passed away after a short illness in October, 2011.