The complete nucleotide sequences of two parvoviruses isolated from goose and muscovy duck were determined. The two virus genomes share 81.9% nucleotide sequence identity, indicating that they are closely related. The coding regions are bracketed by inverted terminal repeats containing palindromes. This is similar to the genome organization of human parvoviruses, adeno-associated virus 2, and B19. Amino acid sequence comparison shows that the closest relative of the goose and muscovy duck parvoviruses is adeno-associated virus 2. This is surprising, because the goose and muscovy duck parvoviruses do not require any helper virus for productive replication, suggesting that adeno-associated virus 2 has been derived from a helper-independent ancestor.