The Masters and Johnson research team, made up of William Masters and Virginia E. Johnson, pioneered research into the nature of human sexual response and the diagnosis and treatment of sexual disorders and dysfunctions from 1957 until the 1990s.

Their work began in the Department of Obstetrics and Gynecology at Washington University in St. Louis and was continued at the independent not-for-profit research institution they founded in St. Louis in 1964, originally called the Reproductive Biology Research Foundation and renamed the Masters & Johnson Institute in 1978.

In the initial phase of their studies, from 1957 until 1965, they recorded some of the first laboratory data on the anatomy and physiology of human sexual response based on direct observation of 382 women and 312 men in what they conservatively estimated to be "10,000 complete cycles of sexual response." Their findings, particularly on the nature of female sexual arousal (for example, describing the mechanisms of vaginal lubrication and debunking the earlier widely-held notion that vaginal lubrication originated from the cervix) and orgasm (showing that the physiology of orgasmic response was identical whether stimulation was clitoral or vaginal, and proving that some women were capable of being multiorgasmic), dispelled many long standing misconceptions.

They jointly wrote two classic texts in the field, Human Sexual Response and Human Sexual Inadequacy, published in 1966 and 1970 respectively. Both of these books were best-sellers and were translated into more than thirty languages.

They have been inducted into the St. Louis Walk of Fame.