Terrell's career was interrupted when she collapsed into Gaye's arms as the two performed at a concert at Hampden–Sydney College on October 14, 1967.

Terrell was later diagnosed with a brain tumor and had eight unsuccessful surgeries before dying on March 16, 1970, at the age of 24.

According to the Unsung documentary, her sister Ludie said her parents thought Terrell would be a boy and, therefore, she would be named after her father.

[3] While it was not thought to be of significance at the time, family members later stated that these headaches might have been related to her later diagnosis of brain cancer.

[5] In 1960, Terrell signed under the Wand subsidiary of Scepter Records after being discovered by Luther Dixon.

Having been introduced to James Brown, she signed a contract with him and began singing backup for his Revue concert tours.

Terrell enrolled in the University of Pennsylvania, where she majored in pre-med, staying at the school for two years.

[5] In the middle of this, Terrell was asked by Jerry Butler to sing with him in a series of shows in nightclubs.

In 1966, Terrell recorded two future classics, Stevie Wonder's "All I Do (Is Think About You)" and The Isley Brothers' "This Old Heart of Mine (Is Weak for You)".

After the release of her first single on Motown, Terrell joined the Motortown Revue opening for the Temptations.

The song's B-side, the Marvin Gaye composition "If This World Were Mine", became a modest hit on both charts, No.

All four songs were included on Gaye and Terrell's first duet album, United, released in the late summer of 1967.

[8] In 1967 the Funk Brothers supported Marvin Gaye & Tammi Terrell's live show as backing band.

[11][12] Shortly after her return from Virginia, doctors diagnosed a malignant tumor on the right side of her brain.

Late in 1969, Terrell made her final public appearance at the Apollo Theater, where Marvin Gaye performed.

And back then, you wouldn't ever get the woman's side so that people would assume, fairly or not, he flipped her ass because she provoked him to."

One night on the road in 1963, Terrell left Brown after he assaulted her for not watching his entire performance.

[18] During the Motortown Revue in 1966, Terrell embarked on a torrid romance with The Temptations lead singer David Ruffin.

Terrell told Ebony magazine in 1969 that she believed her emotional state during this relationship was a contributing factor to her headaches, which came after quarrels.

[17] It was rumored that Ruffin also hit Terrell in the head with a hammer, which further complicated her unknown condition.

[17] Due to ongoing complications resulting from a brain tumor, by early 1970, Terrell was using a wheelchair, experienced blindness and hair loss, and weighed only 93 pounds (42 kg).

In addition, his classic album What's Going On, a reflective, low-key work that dealt with mature themes, released in 1971, was in part a reaction to Terrell's death.

[25] Terrell and Marvin Gaye were nominated for Best Rhythm & Blues Group Performance, Vocal or Instrumental for their song "Ain't No Mountain High Enough" at the 10th Annual Grammy Awards in 1968.