For purification of F and S components of the Panton-Valentine leukocidin, an easy three-step method using fast protein liquid chromatography was developed to replace the time-consuming purification procedures previously published. This technique enabled the recovery of 13 and 17 mg of purified F and S, respectively, per litre of culture supernatant. Affinity-purified neutralizing polyclonal antibodies were obtained against each individual component. One hundred and thirty-nine Staphylococcus aureus strains isolated from various clinical samples of hospitalized patients were screened by immunoprecipitation for Panton-Valentine leukocidin (PVL) production. Only 8 strains produced PVL; all originated from injured superficial soft tissues. Contrary to widespread opinion, the 8 PVL-producing strains were never associated with severe infection.