A synthetic peptide vaccine consisting of the amino acids 126 through 134 of the human Wilms' Tumor protein-1 (WT1) with potential antitumor activity. WT1, a tumor associated antigen, is overexpressed in most types of leukemia and in a variety of solid cancers. Vaccination with WT1 126-134 peptide vaccine may induce a WT1-specific cytotoxic T-lymphocyte (CTL) response against WT1 expressing cells, resulting in cell lysis and inhibition of cancer cell proliferation.