A case of infection with a newly described scotochromogenic mycobacterial species, Mycobacterium szulgai, is presented, and all the reported cases are summarized. The disease is characterized by its predominance in middle-aged men, the occurrence of cavitary pulmonary lesions, and a good response to triple-drug therapy. Sputum samples are usually positive on smear. Drug susceptibility studies show a greater degree of susceptibility to several antituberculosis drugs than the usual scotochromogen. Mycobacterium szulgai has frequently been confused with other atypical mycobacteria, but serologic and other laboratory characteristics are distinct and should allow proper identification.