A humanized monoclonal antibody directed against the human tumor-associated antigen GD2, with potential antineoplastic activity. Upon vaccination, the humanized monoclonal antibody 3F8 stimulates antibody-dependent cell-mediated cytotoxicity (ADCC) against GD2-expressing tumor cells. GD2, a disialoganglioside with expression in normal tissues restricted primarily to the cerebellum and peripheral nerves, is commonly expressed at high levels on tumors of neuroectodermal origins such as melanomas and neuroblastomas. Compared to the murine monoclonal antibody 3F8 (m3F8), the humanized form does not cause a human anti-mouse antibody (HAMA) response and shows enhanced ADCC activity.