The complete nucleotide sequence of the c-fos(human) gene, the human cellular homolog of the oncogene (v-fos) of Finkel-Biskis-Jinkins murine osteosarcoma virus, has been determined. The c-fos(human) gene contains four discontinuous regions when compared with the v-fos gene. Three of the discontinuities are flanked by sequences characteristic of introns, while the fourth discontinuity is due to a deletion of 104 base pairs in the v-fos gene. As a consequence of the deletion, the predicted c-fos(human) and v-fos gene products differ at their carboxyl termini. Transcripts of 2.2 kilobases from the c-fos(human) gene have been identified in human cells. The sizes of these transcripts are in close agreement with the size expected from the nucleotide sequence after removal of introns.