In Graves’disease an increased immunological activity against glycoconjugate antigens is observed. Since gangliosides seem to be important for thyroid stimulation we searched for the presence of antiganglioside antibodies in Graves’patients sera by the immunoenzymatic method. Antibodies against some of 12 different gangliosides used in this study were found in 22% of the patients. However, in most cases the titer of antiganglioside antibodies was very low. Only the serum from one patient reacted with FucGMl ganglioside at the dilution up to 1 : 1300. Anti-FucGM 1 antibodies were present in serum samples of this patient taken before and during the treatment when she was hyper-hypo- and euthyroid. The lack of relation of the anti-FucGM 1 antibody titer to the thyroid status of this patient, and the very low titer of antiganglioside antibodies in sera of some other patients, suggest that the presence of these antibodies has no close connection to the thyroid disease.