A clinical and bacteriological comparison of tetracycline and erythromycin was carried out in 40 patients with papulopustular acne vulgaris. Twenty patients received 250 mg of tetracycline BID and 20 received 250 mg of erythromycin BID for four months. Clinically, 19 (95%) of patients treated with tetracycline and 17 (85%) of those treated with erythromycin had improvement ranging from moderate to very good. Both drugs also reduced the microflora both in the pustules and on normal skin from the same patients. Three patients given tetracycline and one given erythromycin reported mild side effects. Thus both antimicrobial agents were effective and safe in treating acne vulgaris.