The nucleotide sequence of seven exons of the human c-fgr gene, a cellular homolog of the oncogene of Gardner-Rasheed feline sarcoma virus, was determined. Twenty-six independent genomic clones were obtained from a human gene library with a DNA clone of Y73 avian sarcoma virus oncogene, v-yes, as a probe under relaxed hybridization conditions. Restriction mapping and partial sequence analyses revealed that two of these clones were derived from the c-fgr gene, distinct from the c-yes gene. Interestingly, the splicing points of the c-fgr gene were identical with those of the c-src gene throughout the seven exons, suggesting that the two proto-oncogenes were generated by gene duplication of an ancestral gene containing intervening sequences. On RNA blot hybridization the major transcript was found to be 2.6 kilobase long. Two additional transcripts of 3.5 and 4.7 kilobases were also detected. Furthermore, karyotype analysis of several human-mouse hybrid cells and Southern blot analyses of DNAs of the hybrids with a human c-fgr locus-specific probe showed that this gene is located on chromosome 1.