A double-blind, random distribution study showed that a lower than recommended dose of minocycline--50 mg twice daily--was as effective as a dose of 250 mg twice daily of tetracycline for treatment of acne vulgaris in comparable patient groups, and that minocycline produced no vestibular side effects at the lower dosage. Like tetracycline, minocycline did not produce the phototoxicity associated with demeclocycline or the life-threatening colitis associated with clindamycin. Patients in this study did not develop a resistance either to minocycline or to tetracycline. Studies of the use of minocycline in patients who have developed tetracycline resistance and long-range studies of patients on the new lower dose of minocycline are now underway.