Haruo Sugi graduated from the Postgraduate School of the University of Tokyo, Japan, with a PhD in 1962 and was appointed instructor in the Department of Physiology of the University of Tokyo. From 1965 to 1966, he worked at Columbia University as a research associate and at the National Institutes of Health as a visiting scientist. He was a professor in and chairman of the Department of Physiology, Teikyo University Medical School, Japan, from 1973 to 2004, when he became emeritus professor.