A 36-year-old woman developed concurrent Pneumocystis carinii pneumonia (PCP) and cytomegalovirus (CMV) pneumonia. She was diagnosed as lupus nephritis two years ago and was on immunosuppressive therapy with prednisolone and mycophenolate mofetil. She developed dyspnea with moderate hypoxemia. Chest X-ray and HRCT showed diffuse interstitial infiltration and ground glass opacity. The diagnosis of concurrent PCP and CMV was performed by the virus culture and PCP PCR of bronchoalveolar lavage fluid. She recovered following treatment with trimethoprim-sulfamethoxazole, prednisolone, gancyclovir for three weeks.