Denmark was represented at the Eurovision Song Contest 1978 with the song "Boom Boom", written and performed by the group Mabel. The Danish participating broadcaster, (DR), organised the 1978 in order to select its entry for the contest. This marked Denmark's return to Eurovision after an 12-year absence.
(DR) held the 1978 on 25 February at the Tivoli Concert Hall in Copenhagen, hosted by Jørgen de Mylius. The musical director was Ole Kurt Jensen. Six songs took part with the winner being decided by votes from eight regional juries.
Other participants included both Denmark's first Eurovision winner, Grethe Ingmann, and their eventual second winners, the Olsen Brothers.
On the night of the final Mabel performed 16th in the running order, following 's "Charlie Chaplin" by Tania Tsanaklidou and preceding 's "Parlez-vous français ?" by Baccara. At the close of voting "Boom Boom" had received 13 points, placing Denmark 16th of the 20 entries. The Danish jury awarded its 12 points to .