We report four female patients with Graves' disease with positive ANA antibodies and possibility for development of systemic lupus erythematosus. All four patients have been treated with antithyroid drugs. SLE symptoms have appeared from 4 to 12 months after the beginning of therapy with methysol in two of them. The third patient had no symptoms for SLE, but her ANA, anti-DNA, and antihistone antibodies had been positive at the time of the onset of thyrotoxicosis. The fourth patient had alopecia areata with positive ANA and antihistone antibodies.