"Rainy Dayz" is a 2002 single by Mary J. Blige & Ja Rule, taken from Blige's re-release of her seventh album No More Drama. The Irv Gotti produced duet became another hit for both, while peaking at #12 on Billboard ' s Hot 100 and #17 in the UK.

The track was originally written for TLC but the group turned the track down. References to TLC being the group in mind when the track was written can be heard in the lyrics "We’re always livin’ so crazy and sexy and cool" (in reference to their album Crazy Sexy Cool and "Baby didn’t we tell you before about chasin’ those waterfalls" (in reference to their hit single "Waterfalls").