The iconic group reformed for a surprise performance in Sweden.
The legendary foursome attended a private party to celebrate the 50-year partnership between songwriters Bjorn Ulvaeus and Benny Andersson.
During the gala, Agnetha Faltskog and Anni-Frid Lyngstad performed the Abba song The Way Old Friends Do. Ulvaeus and Andersson joined in at the end of the song, marking the band's first public performance in 30 years.
Sadly, no footage has appeared online but images of the quarted have appearred on social media.
Since winning the Eurovision Song Contest in 1974, Abba have sold almost 400 million albums around the world. Mamma Mia!, the musical based on their hits and produced by Ulvaeus and Andersson, has been seen by more than 50 million people.