Two cases of HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosis nigricans) are presented. The first case corresponds to a female with a systemic lupus erythematosus and acanthosis nigricans in which an insulin resistance was documented; the patient was in amenorrhea with severe hypoestrogenism, although she did not have clinical signs of hyperandrogenism and serum androgen levels were normal. This case corresponds to a HAIR-AN syndrome associated to autoimmune diseases or type A of Kahn. The second case is a young female with clinical signs of hyperandrogenism associated to high testosterone levels; she had acanthosis nigricans and fasting and postprandial hyperinsulinemia. Probably, this case corresponds to a type A or C HAIR-AN syndrome in which there is a decrease in the number of insulin receptors or a post receptor defect in insulin action.