We have determined the complete nucleotide sequences of adeno-associated virus 3 (AAV-3) and generated an infectious clone. The single-stranded DNA genome of AAV-3 is 4726 nucleotides in length. The positive strand contains two large open reading frames; the left open reading frame encodes the nonstructural proteins and the right open reading frame encodes the structural proteins. The coding regions are flanked by identical inverted terminal repeat sequences containing palindromes. AAV-3 has little homology with the autonomous parvoviruses or erythroviruses but has 82% overall sequence homology with AAV-2. At the amino acid level there was 88% homology with AAV-2 nonstructural (Rep) proteins and 87% homology with AAV-2 capsid proteins. In addition, AAV-3 differed importantly from AAV-2 in the lack of a typical promoter sequence (TATA box) at p40 and the presence of the consensus sequence for adenovirus-related transcription factor E4F binding within the upstream region of the p5 promoter. These results suggest that AAV-3 not only consists of serologically distinct structural proteins but that viral propagation also may be controlled by different gene regulatory elements at the transcription level. The infectious clone confirmed the sequence and may be useful for developing new vectors for gene therapy.