A peptide vaccine containing the prostate specific antigen (PSA) with potential antineoplastic activity. PSA, a glycoprotein secreted by prostatic epithelial and ductal cells, is overexpressed in prostate cancer cells and is used as a tumor marker for both diagnosis and treatment evaluation. Vaccination with PSA peptide vaccine may produce anti-PSA antibodies as well as elicit a cytotoxic T-cell (CTL) response against prostate cancer cells expressing this antigen, thereby decreasing tumor cell growth.