For the past 3 years, comedones, papules, pustules, and nodules had been erupting on the face of a 16-year-old boy. Acne vulgaris had been diagnosed. Topical tetracycline cream and oral tetracycline were used without success. Drs Alexander K. C. Leung and Massoud Rafaat of Calgary, Alberta, comment that the term “acne” is derived from the Greek word “acme,” meaning “prime of life.” Acne vulgaris is primarily a disease of adolescence, although it may persist into adulthood. Obstruction of the pilosebaceous canal precedes the development of the lesion. An accumulation of adherent keratinized cells within the canal forms an impaction that obstructs the flow of sebum. Dihydrotestosterone is the tissue androgen that causes hypertrophy of the sebaceous gland, increased production of sebum, and keratinization of the cells. Colonization with the anaerobic bacterium, Propionibacterium acnes, increases dramatically during puberty and plays a role in this disease. Lipase from P acnes enzymatically hydrolyzes about half of the triglycerides in the pilosebaceous gland into free fatty acids and glycerol. These cytotoxic fatty acids are released into the skin through follicular breakdown and contribute to the inflammatory reaction.1 Isotretinoin, 0.5 to 2 mg/kg/d, is the treatment of choice for refractory acne vulgaris. This drug decreases sebum production, follicular keratinization, and the intrafollicular concentration of P acnes. Side effects are doserelated; they include cheilitis, xerosis, conjunctivitis, pruritus, epistaxis, drying of the nasal mucosa, and xerostomia. Because of the agent’s teratogenic effect on the fetus, female patients who take this medication must avoid pregnancy. This patient’s acne vulgaris was successfully treated with isotretinoin.