Captain B.J. Hunnicutt, when asked, mentions that the initials "B.J." stand for "anything you want," and even Hawkeye that the initials are derived from the names of his parents, Bea and Jay.

Hunnicutt resided in Mill Valley, California, before he was drafted. He was educated at Stanford University and was a member of the Tau Phi Epsilon fraternity. He is a third-generation doctor in his family. He went through his military training at Fort Sam Houston.

He is devoted to his wife Peg (née Hayden) who writes many letters to him while he is in Korea. The couple have a daughter, Erin, who was born shortly before B.J. left for Korea. He is a skilled surgeon, willing to take extraordinary measures to save a patient. For example, he's willing to undertake an experimental procedure (for the time) by using a primitive open-chest defibrillator and open-chest heart massage.