Mycobacteria are only exceptionally responsible for infection of the skin and soft tissues. A Mycobacterium chelonae myositis occurred in an immunodepressed patient.A 49 year-old man, treated for many years with corticosteroids for vasculitis of the lower limbs associated with rheumatoid polyarthritis, was hospitalized for invasive pulmonary aspergillosis. Ten days later he developed myositis of the right arm with multiple subcutaneous abscesses. Culture of the purulent substance isolated Mycobacterium chelonae. Treatment with ciprofloxacine and clarithromycine led to the regression of the lesions. He was followed-up for 12 months.M. chelonae is found in large quantities in the environment. Infection with this mycobacteria is enhanced by immunodepression, notably that secondary to corticosteroid therapy. Resistance to antibiotics are frequent. Clarithromycine is highly effective against this mycobacteria. Bi-therapy is recommended to avoid the emergence of resistance.