The B-raf gene was localized to human chromosome region 7p11-7qter by Southern blot analysis of its segregation in a panel of rodent-human hybrids, using a B-raf cDNA clone. Chromosomal in situ hybridization refined the localization to 7q33-36. Analysis of genomic B-raf clones identified a B-raf pseudogene in addition to the active gene. Based on the chromosomal mapping data we conclude that the pseudogene is located near the active gene.