Nontropical pyomyositis as a cause of subacute, multifocal myalgia in the acquired immunodeficiency syndrome. We report a case of nontropical pyomyositis in a patient with acquired immunodeficiency syndrome and disseminated Mycobacterium avium infection, in which severe myalgia was the presenting symptom over several weeks. Multifocal muscle lesions were identified by gallium scanning and magnetic resonance imaging techniques. The epidemiology, possible pathogenesis, clinical features, diagnostic imaging, and therapy are reviewed. Early suspicion of nontropical pyomyositis in severely immunocompromised patients with "cryptic" myalgia is recommended. 