A lukF gene encoding F-component of Staphylococcal leukocidin from methicillin resistant Staphylococcus aureus (MRSA) was cloned. The nucleotide sequence of lukF gene was determined. The sequence data have revealed an open reading frame, which encodes a polypeptide with 323 amino acid residues. Inspection of the amino acid sequence deduced from nucleotide sequence of lukF and that from F-component of leukocidin from S. aureus V8 clarified that pre-matured F-component contains a typical signal peptide at the NH2 terminus and ATG starting codon for pre-matured F-component was present one base downstream to the TGA which is translation termination codon for S-component of leukocidin [A. Rahman et al. (1991) Biochem. Biophys. Res. Commun. 181, 138-144]. The nucleotide sequence of 5'-flanking region of lukF showed the presence of the consensus sequence of ribosome binding site in the internal region of the structural gene of S-component. The lukF was transcribed in the same direction as that of lukS. No Pribnow box can be discerned in the intercistronic region between the lukS and lukF genes. The amino acid sequence homology between S- and F-components was 31%. F-component was expressed in Escherichia coli DH5 alpha harboring plasmid pFRK92 which contained lukF gene.