A total of 29 patients with cancer and neuropathies of unknown origin that were possibly paraneoplastic were tested for antiganglioside antibodies by immunodot blot and ELISA. None of the patients had onconeural antibodies. They were compared with 41 normal subjects and 187 patients with metabolic or idiopathic neuropathies. Antiganglioside antibodies, mainly IgM anti-GM1, were more frequently found in the patients with cancer than in the control groups. However, the levels of antibodies were not different from those of the controls. There was no correlation with the pattern of the neuropathy. These results do not support the hypothesis that antiganglioside antibodies are frequent and major immunological targets in paraneoplastic neuropathies.