An iodine 131-radiolabeled small-molecule benzamide compound with potential antineoplastic activity. The benzamide moiety of ioflubenzamide I-131 binds to melanin, selectively delivering a cyotoxic dose of gamma and beta radiation to melanin-expressing tumor cells. Melanin pigments, polymer derivatives of the amino acid tyrosine, are over-expressed in approximately 40% of melanomas.