MAC lung infections are a growing public health problem. The ATS / IDSA 2007 guidelines for the treatment of these non-tuberculous mycobacterial infections recommend the use of a macrolide or azalide (clarithromycin or azithromycin), rifampicin or rifabutin and ethambutol. For MAC disseminated infections, several studies have compared combinations containing clarithromycin or azithromycin and found no significant difference in efficacy. No randomized controlled trials have been performed for pulmonary infections to compare clarithromycin and azithromycin in terms of efficacy. Clarithromycin is often used as a first-line treatment in France, but its tolerance is often poor, particularly in terms of risk of hepatitis, metallic taste in the mouth, nausea or vomiting, and it interacts with many drugs via cytochrome p450 . In particular, it increases the toxicity of rifabutin, in particular in terms of uveitis. Azithromycin has fewer side effects especially less digestive toxicity and drug interactions than clarithromycin. The hypothesis is therefore that the efficacy of azithromycin would be non-inferior in comparison with that of clarithromycin.