Mycobacterium avium complex (MAC) is the most common nontuberculous mycobacterial pathogen in Japan. There are 2 major types of clinical manifestations of MAC disease, including fibrocavitary disease and nodular bronchiectatic disease. Primary treatment of MAC disease is medical treatment. Standard multidrug regimens employ clarithromycin, rifampicin, and ethambutol. Aminoglycoside (streptomycin or kanamycin) is added if necessary. Patients whose disease is predominantly localized to 1 lung and who can tolerate resectional surgery may be considered for surgery under the following circumstances; poor response to drug therapy, the development of macrolide-resistant MAC disease, or the presence of hemoptysis. Surgery for MAC lung disease can achieve favorable treatment outcome. However, surgery is associated with significant morbidity, especially when pneumonectomy is performed. When surgical intervention is considered necessary for MAC patients, pulmonary resection should be performed before MAC lung disease has progressed too extensively to avoid pneumonectomy.