Seventy patients with rosacea were treated with systemic tetracycline for 6 months. Sixty-eight of them cleared with treatment. After withdrawal of the drug seventeen relapsed immediately and the overall relapse rate over 4 years was 69%. The serum tetracycline levels were not significantly different in two patients who failed to respond. Six patients had rosacea keratitis and responded dramatically within 1 month. Symptoms recurred as the drug was withdrawn. It is suggested that rosacea patients with keratitis should receive early and prolonged tetracycline medication.