Pneumocystis carinii pneumonia (PCP) is an opportunistic infection, which results in increased morbidity and mortality during the posttransplant period. In our study we retrospectively analyzed 713 patients, who were followed up at the Transplantation Out-Patient Clinic of Istanbul School of Medicine during 1983 -1998; among whom 9 (% 0.13) were complicated with PCP (7 male, 2 female, mean age: 36.1 years). Four of them got their kidneys from cadaveric and five from living donors. Three patients had acute rejection. As maintenance immunosuppression, 2 patients had double and others had triple therapy. Patients were complicated with PCP on average 4.5 (3 - 8) months posttransplant. During the infection their mean serum creatinin level was 1.6 (1.3-1.7) mg/dl.. Pneumocystis carinii pneumonia was diagnosed by bronchoscopy and the pathological and immunofluorescent antibody examination of bronchoalveolar lavage material. Four patients also had cytomegalovirus infection. Trimethoprim at a dose of 20 mg/dl was administered in the combination form as co-trimoxazole, parenterally to one patient and orally to the others. Three patients died; while all the others survived with preserved graft functions. Pneumocystis carinii pneumonia should always be suspected in renal transplant patients presenting with sudden onset respiratory distress and cough and invasive techniques should be instituted early to initiate the appropriate therapy.