Magnum, P.I. is an American tv show starring Tom Selleck as Thomas Magnum, a private eye living on Oahu, Hawaii. The show ran in the American CBS television network from 1980 to 1988 in broadcast. According to the Nielsen ratings, Magnum, P.I. consistently ranked in the top twenty U.S. tv programs throughout the initial five years which the show was originally broadcast in the United States. Originally appearing in a prime time American network timeslot of 8 Eastern on Thursdays, Magnum, P.I. was among those highest-rated shows on U.S. tv.