The cDNA clones encoding two isoforms of bovine stem cell factor (bSCF) were obtained using reverse transcriptase-polymerase chain reaction, and their sequences were determined. The deduced amino acid sequences of the longer and shorter isoforms of bSCF consist, respectively, of 274 and 246 residues and show a high degree of identity to those of SCFs of different animal species. Northern blot analysis with the cDNA revealed the expression of a 5.8 kilobase bSCF RNA in fetal bovine tissues.