A 39-year-old man with pulmonary disease due to Mycobacterium xenopi is described. He had received prednisone and azathioprine for 5 years and prednisone in combination with cyclosporin A for 1 year in an effort to prevent rejection of his renal transplant. Shortly after the renal allograft was removed because of chronic rejection, the patient developed dyspnea and a decrease in vitality. He had no history of preexisting lung disease. A chest roentgenogram showed multiple nodular infiltrates in both lungs. M. xenopi was cultured from three sputum samples. The organism was susceptible to isoniazid, streptomycin, ethambutol, rifampin, pyrazinamide, and ethionamide. The patient was treated successfully with isoniazid, ethambutol, and rifampin for 3 months and with isoniazid in combination with rifampin for an additional 9 months, while he was maintained on continuous ambulatory peritoneal dialysis (CAPD). The literature on mycobacterial disease, especially in renal transplant recipients and patients on CAPD, is reviewed.