Pneumocystis carinii pneumonia (PCP) is one of the most common causes of infection in patients with HIV infection. With the development of effective prophylactic agent, the incidence of PCP in patients with HIV infection has been declining. On the other hand, however, the incidence of PCP has been increasing in immunocompromised hosts without HIV infection, such as rheumatoid arthritis, bons: marrow transplantaion and Beh4;et syndrome. The increased occurrence of PCP in nonHIVinfected subjects has been attributed to several factors, such as use of stronger immunosuppressive regimens, higher awareness of PCP, advanced diagnostic technology and nosocomial spread of P. carinii. The occurrence of PCP in patients who receive immunosuppressive drugs for autoimmune disease has not been well known in Korea. We report a patient with Behl;et syndrome who suffered from PCP after immunosuppressive drugs.