"The Onion Song" was a hit for soul singers Marvin Gaye and Tammi Terrell in 1969. It reached the top ten overseas, and was a more modest hit in the U.S.
Originally assigned to Diana Ross & The Supremes, the song was reassigned to Gaye and Terrell in early 1969. Terrell, then suffering from a brain tumor, was unable to perform onstage after an October, 1967 performance where she fell before being carried offstage by Gaye for medical treatment. She found out she had brain cancer, a result of Terrell experiencing headaches since childhood. For many years, co-songwriter Valerie Simpson was reported to have sung on this recording with Gaye. However, Simpson, in recent years, denied the claim, saying she only recorded with Marvin as a vocal guide for Terrell. In David Ritz's biography of Gaye, Divided Soul, Gaye alleged that Simpson sung on the record because Terrell was "too ill to record". Terrell was in the studio, it was claimed, but was using a wheelchair.
The song, which reflected social consciousness, became Gaye & Terrell's biggest hit in the United Kingdom, entering the singles chart on 29 November 1969 and peaking at #9 on 9 December prior to Terrell's March 16, 1970 death.