In the course of a randomized, comparative, clinical study, 50 patients with acne vulgaris received systemic treatment with a single daily dose of 50 mg doxycycline or two daily doses of 50 mg minocycline. At the completion of the 12-week treatment, cure or improvement of acne was found in 78% of the patients in the doxycycline group compared to 82% in the minocycline group. The rate of unsatisfactory therapeutic results was 22% in the doxycycline group and 18% in the group of patients treated with minocycline. The results showed no significant difference between the clinical efficacy of treating acne vulgaris with doxycycline at a daily dose of 50 mg and 100 mg of minocycline daily, a fact which has already been demonstrated by earlier studies.