Atypical mycobacterial infection is seldom accompanied by pleural involvement. We report a very rare case of Mycobacterium avium-intracellulare pleuritis with massive pleural effusion. The patient was a non-immunocompromised 35-year-old Japanese male with insidious onset of fever, chest pain and anorexia. The pleural effusion gradually resolved with empirical antimycobacterial treatment, leaving considerable pleural adhesion and thickening.