Chlorpromazine has been reported to interfere with the action of alloantibodies directed against HLA-A1. We attempted to replicate this finding using peripheral blood lymphocytes from 3 healthy donors in a complement-mediated lymphocytotoxicity assay. We were unable to find evidence of interference between chlorpromazine and the anti-HLA sera tested. Possible reasons for the difference between our finding and the previous report, as well as the implications for schizophrenia, are discussed.