The genome of Duck circovirus (DuCV) is circular and 1996 nts in size. Two major open reading frames were identified, encoding the replicase (V1) and the capsid protein (C1). A stem-loop structure comprising the nonamer 5'-TATTATTAC, conserved in all circo-, nano- and geminiviruses, was found. Unique to DuCV, the region between the 3'-ends of the rep and cap gene contains four repeats of a 44-bp sequence. Phylogenetic analysis shows close relation of DuCV with Goose circovirus and suggests classification of DuCV as a new member of the genus Circovirus of the virus family Circoviridae.