The cytochrome P450 2F (CYP2F) subfamily genes are currently known only from cDNA sequences in human, mouse, rat and goat. Compared to other divisions of the CYP2 gene family, the CYP2F subfamily is unusual in having few genes per species and in being selectively expressed in lung tissues. Sequencing genomic DNAs from human and gorilla has allowed us to determine the number of CYP2F subfamily loci in these species, the sources of known human transcripts, and the functional status of CYP2F loci in both primates. This information will make accurate genotyping of the functional and medically significant CYP2F1 gene possible in humans. Comparisons across multiple species show that the sequences of CYP2F subfamily genes are very conserved in mammals for intronic as well as exonic DNA.