Background: Recently identified porcine circovirus-like virus P1 has the smallest DNA viral genome. In this study, we identified the viral genes and their corresponding mRNA transcripts. Results: The RNAs of P1, synthesized in porcine kidney cells, were examined with northern blotting and PCR analyses. Eight virus-specific RNAs were detected. Four mRNAs (open reading frames (ORFs) 1, 2, 4, and 5) are encoded by the viral (-) strand and four (ORFs 3, 6, 7, and 8) are encoded by the viral (+) strand. All proteins encoded by the ORFs of the P1 virus are less than 50 amino acids in length, except that encoded by ORF1 (113 amino acids). Conclusions: We show a very complex viral transcription pattern in P1-infected cells.