A γ EMBL3 clone containing the first three exons along with part of the 4th exon of the rat poly(ADP-ribose) polymerase gene was isolated from a genomic DNA library. This clone also contains 6.6 kbp of upstream sequences. Nucleotide sequence analysis of the proximal 5' 670 nucleotides flanking the major RNA start site of the rat gene does not reveal significant global homology with the same region of the human gene, but a series of short sequences are identical. Among these sequences are found two putative Spl binding sites along with a decanucleotide sequence responsible for the attachment of the transcription factor AP-2.