BACKGROUND: Insulin resistance syndrome shows extreme insulin resistance and is associated with acanthosis nigricans. We can differentiate it into type A insulin resistance that has insulin receptor defect, and type B insulin resistance due to insulin receptor autoantibody. Type B insulin resistance was firstly described by Kahn in 1976. It was often found in adult female and showed autoimmune characteristics. As clinical characteristics, there are hyperglycemia, hypoglycemia, hyperinsulinemia, extreme insulin resistance and acanthosis nigricans. METHODS: We investigated 17 insulin receptor autoantibody positive cases and 8 cases of normal control who had visited Wonju Christian Hospital from October 1994 to December 1995. Among insulin receptor autoantibody positive subject, male was 4 cases and female 13 cases. Their mean age was 42.2. We compared patients who had insulin receptor antibody positive acanthosis nigricans(IRA) with normal controls. IRA patients were 6 cases(35.3%) of nomal glucose tolerance, 11 cases(64.7%) of abnormal glucose tolerance including overt diabetes mellitus. RESULTS: The 11 cases(64.7%) among IRA patrents were obese and 13 cases(76.5%) had hyperininsulinemia. In IRA patients, mean serum insulin concentration during oral glucose tolerance test was 202.1mU/mL and it was greater than 46.3 of normal controls. Insulin sensitivity in 1.79mg/L * mM * xmU * min normal controls was higher than 0.74mg/L * mM * min of IRA patients. CONCLUSION: IRA patients showed abnormal glucose tolerance including overt diabetes millitus, severe insulin resistance, hyperinsulinemia and obesity.