Premature ovarian failure (POF) is a disorder of heterogeneous etiology, and autoimmunity has been suspected as one cause of POF. The steroidogenic enzyme, 3beta-hydroxysteroid dehydrogenase (3betaHSD), has been characterized as a potential autoantigen in POF as well as in insulin-dependent diabetes mellitus (type 1 diabetes). Here we studied the presence of steroid cell antibodies (SCA), autoantibodies to 3betaHSD and to two other known autoantigens in ovarian failure, steroidogenic enzymes 17alpha-hydroxylase (P450c17), and side-chain cleavage enzyme (P450scc) in POF patients and patient groups with autoimmune polyendocrinopathy syndromes type 1 and 2 (APS1 and -2), isolated Addison's disease, type 1 diabetes, and healthy controls. The SCA were found in 2 of 48 POF, 11 of 15 APS1, and 1 of 9 APS2, and autoantibodies to in vitro translated 3betaHSD protein were detected in 1 POF serum associated with Addison's disease and 3 APS1 sera. All 3betaHSD precipitating sera were also positive for SCA. However, no SCA or 3betaHSD autoantibodies were found in 38 Addison's disease, 28 type 1 diabetes, and 71 healthy control sera. In analysis of autoantibodies to P450c17 and P450scc, antibodies to these enzymes were not found in POF sera, but were found in 10 and 12 APS1 patient sera, respectively, and 1 APS2 patient serum contained anti-P450c17 antibodies. Our results show that autoantibodies to 3betaHSD in POF patients are rare and are also found in patients with APS1.