Ninety-three consecutive patients with adult chlamydial ophthalmia were treated with four different regimens of oral doxycycline. In patients treated with a single dose of 5 mg/kg of body weight (300 mg) of doxycycline the severity of clinical signs was reduced, and in half of the patients shedding of the infective agent was stopped. Treatment with a weekly dose of 300 mg of doxycycline for three weeks or a daily dose of 1.5 mg/kg of body weight (100 mg) for one week produced a clinical and microbiological cure in 100% of patients. However, in some of these patients mild to moderate papillary responses were present up to six months from completion of the treatment. The best results were obtained with a daily dose of 100 mg for two weeks, which produced rapid clinical and microbiological cure in all patients.