SETTING: Kyoto, Japan.OBJECTIVE: To determine predictors of 5-year mortality in pulmonary Mycobacterium avium-intracellulare complex (MAC) disease.DESIGN: Retrospective study of 164 patients diagnosed with pulmonary MAC disease between 1999 and 2005 and followed for 5 years.RESULTS: Overall 5-year mortality was 28.0%. Among 117 patients with microbiological outcomes, 54 were treated (treated MAC patients) and 24 were not treated and did not experience sputum culture conversion during follow-up (untreated chronic MAC patients); 39 patients were not treated and experienced sputum culture conversion. Five-year all-cause overall mortality among the 78 patients with definite MAC disease (including treated and untreated chronic MAC patients) was 25.6%. The mortality rate was 33.3% for untreated chronic MAC patients only vs. 22.2% for treated MAC patients (P = 0.30). After adjustment for clinical, microbiological and radiological confounders, independent factors for 5-year mortality were a high Charlson comorbidity index in cases with definite MAC disease (hazard ratio HR 1.76) and untreated chronic MAC (HR 3.08), and presence of cavitary lesions in cases with definite MAC disease (HR 1.82) and treated MAC patients (HR 3.91).CONCLUSION: Patients with cavitary lesions require immediate treatment for sputum culture conversion and to improve their chances of survival.