Sixty-three strains ofCorynebacterium acnes (C acnes)were incubated individually in vitro with three representative triglycerides. Consistent differences were found in their ability to hydrolyze these triglycerides. Seventy-five percent of strains ofC acnesisolated from patients with acne vulgaris split C12triglyceride (trilaurin), 56% hydrolyzed C16triglyceride (tripalmitin), and 88% cleaved C18:1triglyceride (triolein). In comparison, 42% of isolates of C acnes from patients without acne vulgaris hydrolyzed C12triglyceride (trilaurin), 17% of C acnes strains split C16triglyceride (tripalmitin), and 58% split C18:1triglyceride (triolein). The differences were significant to the 2% confidence level. The results suggest that distinctive strains ofC acnesinhabit the sebaceous follicles of the Tetracycline hydrochloride (10μg/ml and 30μg/ ml) blocked the in vitro hydrolyzing activity of six strains of C acnes known to possess such splitting abilities.