"3 a.m. Eternal" is a song by British acid house group the KLF, taken from their fourth and final studio album, The White Room (1991). Numerous versions of the song were released as singles between 1989 and 1992 by their label KLF Communications. In January 1991, an acid house pop version of the song became an international top ten hit single, reaching number-one on the UK Singles Chart, number two on the UK Dance Singles Chart and number five on the US Billboard Hot 100, and leading to the KLF becoming the internationally biggest-selling singles band of 1991.

The KLF are a British electronic band who originated in Liverpool and London in the late 1980s. Scottish musician Bill Drummond and English musician Jimmy Cauty began by releasing hip hop-inspired and sample-heavy records as the JAMs. As the Timelords, they recorded the British number-one single "Doctorin' the Tardis", and documented the process of making a hit record in a book The Manual . As the KLF, Drummond and Cauty pioneered stadium house and, with their 1990 LP Chill Out, the ambient house genre. The KLF released a series of international hits on their own KLF Communications record label and became the biggest selling singles act in the world in 1991.