The character of Quincy was based on the real-life Los Angeles County Medical Examiner Dr Thomas Noguchi, who became famous for his often controversial conclusions. He performed autopsies on many stars including Marilyn Monroe, Natalie Wood and John Belushi. In true Quincy-style, he raised doubts about the official account of Robert F. Kennedy's assassination by showing that Sirhan Sirhan could not have fired the fatal shot. He also acted as a technical advisor on the show. The show's concept was adapted from the Canadian series Wojeck (1966).
Marc Scott Taylor was originally hired as a technical advisor but became a semi-regular cast member because he could operate electron microscopes and other complex instruments. It was more cost effective to give him a recurring bit-part than to train the actors to operate the equipment convincingly. His role was greatly expanded in an episode in which "Sam" had been poisoned and "Mark" helped Dr. Quincy save his life.
It originally debuted during the final season of The NBC Sunday Mystery Movie. When the show did well in the ratings NBC decided to upgrade it to a weekly series, especially since it looked like The Sunday Mystery Movie would be canceled. It's place in the rotation was assumed by the new show Lanigan's Rabbi (1976), which was canceled with the others at the end of the 1976-77 season. Quincy was the only element of that series to be spun off on its own.
The regulations of the day prevented the producers from showing Quincy's autopsies on screen. (These regulations have now been lifted and the corpses can be seen on screen in CSI: Crime Scene Investigation (2000), CSI: Miami (2002) and CSI: NY (2004).) The viewer had to rely on Quincy's description of what was going on.
Jack Klugman was part-owner of a horse named Jaklin Klugman, which finished third in the 1980 Kentucky Derby. The horse was named Jaklin by accident (it was a colt), and there is a picture of him hanging in Quincy's houseboat in some of the show's later shows.