A hitherto unrecognized cause of contact dermatitis in California is the widely cultivated plant known as Algerian ivy. This plant, which grows in California (and its close relative, English ivy) causes a dermatitis which is similar to although milder than that caused by poison oak. Dermatitis from this cause occurs most frequently when persons who have become sensitive to it by previous contact trim the plant back in the spring after its seasonal spurt of growth. For persons whose occupations require repeated contact with the plant, dermatitis from this cause is an occupational hazard. Dermatitis from this plant is easily diagnosed by means of a simple patch test. In a series of 12 cases the only effective treatment was with corticosteroid agents.