The nontuberculous mycobacteria are responsible for considerable morbidity in the immunocompromised and immunocompetent host, especially in the older patient with chronic fibrotic or cavitary disease of the lung. Mycobacterium szulgai is a slow growing mycobacterium infrequent in nature and man. Except from a snail and a tropical fish, it has been isolated only from humans and nearly always represents a true pathogen. Three-drug therapy using in vitro susceptibilities as a guide for 12 to 18 months increases the likelihood of success. We present a patient who developed M szulgai pulmonary infection 30 years after an episode of pulmonary tuberculosis. After successful therapy for his M szulgai infection, this patient developed chronic pulmonary histoplasmosis. We review the 25 years of clinical experience with this mycobacteria; particular emphasis is on the presentation and treatment of this very unusual infection.