Mycobacterium scrofulaceum was cultured from two of seven tuberculin reactors in a group of 12 Erythrocebus patas monkeys. One monkey reacted atypically to 0.1 ml of 2.5 mg veterinary tuberculin after having shown no reaction to four previous tests administered at 2-week intervals. The reaction consisted of edema with no induration or erythema at 24 hours and was completely dissipated at 36 hours. Responses to additional tests using veterinary tuberculin (2.5 mg) and Mycobacterium bovis purified protein derivative (1.1 mg) ranged from negative to slightly edematous. Radiographs were suggestive of pulmonary tuberculosis. Extensive granulomas were observed in the lungs, liver and spleen at necropsy. Mycobacterium scrofulaceum was isolated from lung and liver granulomas in this animal and from lung granulomas in another. The atypical skin hypersensitivity and organism isolation from multiple organs suggested Mycobacterium scrofulaceum as the etiologic agent in these animals. Reactions of six other Erythrocebus patas to veterinary tuberculin (2.5 mg) ranged from edematous to indurated.