Demented are Go got their start in Penarth, South Wales, near Cardiff. Initially, the band was disorganised, with Ant Thomas singing, Mark Phillips, or "Sparky," playing drums, a bass player with his hair dyed red, and a "rock icon" with a gold-top Les Paul guitar and leather keks on rhythm guitar. Dick, a veteran of the punk/pub rock circuits, joined the band in early 1983, reshuffled the line up, taught the bass player and generally consolidated things.

After six weeks of rehearsals, the band's first gig was third on the bill to a line up of Crass-type anarchist bands at the Sea Lion in Penarth and was met with good reception. Several years of playing everything from working men's clubs in the Rhondda to the red-light district in Hamburg, turning up at the Klub Foot twenty minutes after they were due on stage. They managed record two songs for their first release on a 1984 compilation, Hell Bent On Rockin' from Nervous Records, a well known record label in the psychobilly scene. In 1986, they released their first album, In Sickness & In Health, on ID Records, which was recorded in less than 24 hours with 90% first takes, with Ray Thompson on bass. Interestingly, the band had more bass players than Spinal Tap had drummers while the core members remained Mark, Ant and Dick.

The band moved to London in 1986 in an attempt to be closer to regular work. Dick left in 1987 after continuing frustration with the direction the band was taking. Undeterred, Lex Luther was recruited to replace Dick, who incidentally coached Lex to bring him up to speed with the band's material, from a DAG-worshipping band that had made a demo with the title of The Granny Snog Bop. This was followed with their second full-length, Kicked Out of Hell, in 1988. The band began extensively touring Europe and gained both a psychobilly and punk following. At this point, the lead singer, Sparky, began becoming addicted to drugs and alcohol, resulting in numerous line-up changes.

In 1989, the band went back to the studio, though without any songs. They were able to write and record an EP for Link Records, The Day the Earth Spat Blood, within the span of three days. Also in 1989 the band provided music for Skrewdriver vocalist Ian Stuart under the name The Klansmen. They released three full-length albums and various singles together up until 1991. The band went on another European tour in 1991, writing and recording their next full-length for Fury Records, Orgasmic Nightmare, on the road. The band would tour almost constantly for the next two years. A second album for Fury Records, Tangenital Madness On A Pleasant Side Of Hell, was recorded in 1993, followed by two tours in Japan. The band was infamous for Sparky showing up to Japanese performances naked.

During a tour in Germany in spring 1995, the band broke up due to Sparky's deteriorating mental state. However, in 1996, Demented are Go reformed to release the EP I Wanna See You Bleed!! for Hell Razor Records. The band toured the west coast of the U.S. in 1997. They would again be known more for their wild stage show, which included on-stage sex with vacuum cleaners.

The band released the full-length Hellucifernation for Crazy Love Records in 1999. However, a European tour for the record's release was cancelled due to Sparky's mental problems returning. The band considered breaking up, but were offered a headlining gig in New Jersey and decided to give Sparky a second try. Upon arrival, Sparky first caused trouble at the hotel by cross-dressing and doing drugs, then setting fire to a surrounding woodland at the music venue. After their soundcheck, the band went to a nearby shopping mall where Sparky pinched a girl's behind. She turned out to only be 16, so he was arrested and charged with molesting a minor. Unable to pay the $60,000 bail, the rest of the band left him in jail and returned to England.

After a month in jail and a $100 fine, Sparky returned to England where the Demented are Go line-up underwent numerous changes. The band went through a period of stability, playing two U.S. tours and recording a live album, Live at the Galaxy, for Crazy Love Records. However, in the summer of 2003, Sparky was arrested numerous times on the road, resulting in more line-up changes. The band continued touring with a revolving line-up lead by Sparky until September 2005, then split again. During a month-long break, a new album Hellbilly Storm was released on German label People Like You Records.

At the beginning of the 2006 U.S. tour, Sparky was detained by U.S. immigration authorities due to his criminal history, and he was sent back to England. It was later found out that the talent agent did not get the needed work permits for the tour. The U.S. tour was cancelled but Demented Are Go still played shows in Europe.