The nucleotide sequence of the DNA encoding the traM, finP and the promoter proximal segment of the traJ gene of the F plasmid has been determined. The predicted amino acid sequence for the traM protein shows that this inner membrane protein contains no signal sequence. The promoters for both the traM and traJ genes have been mapped by in vitro transcription and nuclease S1 protection experiments. No unambiguous location can be assigned to the finP gene but all candidates, if translated, would encode small proteins of between 24 and 52 amino acids.