 Diagnosed with M. avium complex MAC lung disease or other pulmonary mycobacterial infection based on the 1997 version of American Thoracic Society ATS diagnostic criteria and have positive AFB smear or culture for mycobacterial infection at least three months prior to the date of enrollment. Patients with only histological evidence of mycobacterial infection without positive smear or culture will not qualify for this protocol even if they meet the ATS diagnostic criteria for nontuberculous mycobacterial lung infection. 