Backgroud. There is growing a number of Pneumocystis jirovecil pneumonia (PJP) in non-HIV-infected population. These patients typically present with severe disease. The purpose of the study was to describe the population involved, and to assess clinical, biological, and mortality date in solid tumor patients.Methods. The medical charts of all patients with malignancy in our department of Kameda Medical Center between 2008 and 2013 were retrospectively reviewed. The clinical and laboratory data with a proven first episode of PJP diagnosed were abstracted. The diagnosis was made by microscopy with staining or polymerase chain reaction (PCR) of induced sputum or bronchoalveolar lavage (BAL) fluid.Results. Of the 2344 patients with malignancy, six were included in this study, median age 66 (49-80). Underlying cancers were lung cancer (2), gastric cancer (1), rectal cancer (1) prostate cancer (1) and thymic cancer (1). Five patients complained of dyspnea, and one complained of fever. Median duration of disease was 9.5 months. Performance Status (PS) was as follow: three patients were PS-1, two PS-3, and one PS-4. Median lymphocyte count was 1108/mm (3). beta-D-glucan levels were higher than the normal range in 5 patients (median level:28pg/ml). Within 30 days before the diagnosis of PJP, 80% patients were given steroids at median cumulative 30-day dose of 38 mg dexamethasone. No patient had a PCP prophylaxis. One patient died of PJP (17%). The radiographic findings of all patients were diffuse, bilateral, interstitial infiltrates. Conclusion. The incidence of PJP in solid tumor patients is higher than we have expected. The mortality rate was high (17%). This study suggested the possibility of PJP should be considered when we treat malignancy patients whose complains are dyspnea.