"It's a Sin" is a song by English synth-pop duo Pet Shop Boys from their second studio album, Actually (1987). Written by Chris Lowe and Neil Tennant, the song was released on 15 June 1987 as the album's lead single. It became the duo's second number-one single on the UK Singles Chart, spending three weeks atop the chart. Additionally, the single topped the charts in Austria, Denmark, Finland, Germany, Ireland, Norway, Portugal, Spain, Sweden and Switzerland, while reaching number nine on the US Billboard Hot 100.

The Pet Shop Boys are a British synth-pop duo formed in London in 1981. Consisting of primary vocalist Neil Tennant and keyboardist Chris Lowe, they have sold more than 50 million records worldwide, and were listed as the most successful duo in UK music history in the 1999 edition of The Guinness Book of Records.