Knocking at Your Back Door

The song is lyrically about anal sex, as it uses various sexual innuendos throughout the song. Ian Gillan commented:

There's this guy named Redbeard, from a radio station down in Texas. He phoned me up after it had been played on every radio station in America and said, "Is this what I think it's about?" And I said, "Yeah." And he said, "It's amazing, every radio station in America is playing a song written about anal sex and they don't even realize what's going on." And I was like, well it's not in-your-face anal sex, it's just a joke. It just came about with the lyrics. It's no big deal. But it's a humorous thing and not meant to be offensive. And I think it was just an afterthought. It certainly wasn't what inspired the song.[1]

The song, released as a seven-inch single and CD single with "Perfect Strangers" on the second side, in October 1984. In Canada, the second side of the single was the instrumental "Son of Alerik", while in Japan, Spain and the United States a version with "Wasted Sunsets" was released.

"Knocking at Your Back Door" was a permanent part of the band's live set until 1994 and sporadically since then. Live albums that include the track are: Nobody's Perfect (1988), In the Absence of Pink (1991), Come Hell or High Water (DVD, 1994), Live in Europe 1993 (2007), and Live at Montreux 2011 (2011)