Backlash: In Your House was a professional wrestling pay-per-view event produced by the World Wrestling Federation (WWF) promotion and presented by Castrol GTX, which took place on April 25, 1999, at the Providence Civic Center in Providence, Rhode Island. It was the 28th and final event to be promoted under the In Your House banner, as shortly thereafter the WWF decided to give their monthly pay-per-views permanent names; Backlash became the name for the post-WrestleMania pay-per-view beginning in 2000 and retained that name until 2009.

The concept of the pay-per-view was based around the backlash from WWF's premiere pay-per-view event WrestleMania. As such, the main event was a rematch from WrestleMania between Stone Cold Steve Austin wrestling The Rock for the WWF Championship – this time with a special guest referee, Shane McMahon. Lower down on the card, Paul Wight and Mankind had a Boiler Room Brawl to settle matters after their previous encounter, which decided who would referee the WrestleMania event. Triple H also wrestled X-Pac due to Triple H causing X-Pac to lose a match for the European Championship the previous month.