A 42-year-old woman presented with persistent cough, bloody sputum and fever. Her chest X-ray film showed an infiltrative shadow with cavitation in the upper lobe of the left lung. Acid-fast-bacilli were shown by sputum smear staining. The anti-tuberculosis drugs isoniazid, refampicin, ethambutol and pyrazinamide were prescribed, but her symptoms and chest X-ray findings did not improve. Findings of MTD and MAC-PCR were negative but Mycobacterium abscessus was confirmed by sputum culture with the DNA hybridization method. Combination therapy with clarithromycin, amikacin and imipenem/cilastatin for one month improved her symptoms and chest X-ray shadow, and clarithromycin monotherapy was carried out for another ten months. Drug susceptibility tests revealed this mycobacterium was sensitive to clarithromycin and amikacin. To determine the environmental factors related to this infection, several samples were examined. Acid-fast-bacilli were present in a smear from the bath room drain. However, to confirm the infectious routes, longer observation is needed. Moreover, serum amyloid protein A and ESR were useful markers to estimate the clinical course.