"If You Don't Know Me by Now" is a song written by Kenny Gamble and Leon Huff, and recorded by the Philadelphia soul musical group Harold Melvin & the Blue Notes.

The song's composers Kenny Gamble and Leon Huff gave it to Harold Melvin & the Blue Notes, which featured Teddy Pendergrass as lead vocalist, and the actual background vocals done by producers Kenny Gamble, Leon Huff, Carl Helm, and Bunny Sigler.

Simply Red's version of "If You Don't Know Me by Now", recorded for their third studio album A New Flame, was a commercial success in 1989, giving the band their second US number one and also topping the charts of Australia and New Zealand; in the latter country, it was the best-selling single of 1989.

Mick Hucknall admitted he loved Harold Melvin & the Blue Notes' version, and stated he danced to their music when he was 13.

[17] Jerry Smith from Music Week wrote, "Top-notch purveyors of smooth soul, Simply Red deliver this excellent version of the old Harold Melvin & the Bluenotes classic, lifted from their already platinum-selling A New Flame LP.