Synthetic carbohydrate haptens, which are conjugated to carrier human serum albumin molecules [synthetic tumor-associated glycoconjugates (S-TAGs)], were used to immunize mice for monoclonal antibody (MoAb) production. Two of the S-TAGs were composed of haptens related to the Thomsen-Friedenreich (TF) antigen, and their structures are beta Gal(1----3)-beta GalNAc (TF-beta) and beta Gal(1----3) alpha GalNAc (TF-alpha) (Gal = galactose; GaNAc = N-acetylgalactosamine). The third S-TAG was made up of Tn hapten groups of the structure alpha GalNAc-O-serine. MoAbs specific for TF-alpha and Tn were able to be generated. All MoAbs generated against TF-beta cross-reacted with TF-alpha but not with Tn. None of the TF-alpha-specific MoAbs reacted with human carcinomas, whereas several TF-beta and Tn MoAbs were found to react with most human lung, colon, and breast carcinomas. It is believed that this is the first report of the use of synthetic carbohydrate cancer antigens for the production of anticancer MoAbs.