Objective To investigate the clinical features of patients with inflammatory bowel disease (IBD) complicated with Pneumocystis Jiroveci Pneumonia (PJP). Methods We retrospectively analyzed the clinical data of 5 patients who were hospitalized in Peking Union Medical College Hospital from January 2012 to July 2017 for treatment of IBD complicated with PJP. Demographic characteristics,clinical manifestations,treatments,and outcomes were descriptively analyzed. Results Of these five patients,four had ulcerative colitis (UC) and one had Crohn's disease (CD). All patients were males,with an average age of (61.8±1.9) years. All patients were in active disease status and had symptoms including cough and suffocation. Three patients had hypoxemia,among whom two developed type 1 respiratory failure. Three patients were treated with immunosuppressive medications (corticosteroids and/or immunosuppressant drugs) before the diagnosis of PJP. Lymphocyte counts in three patients were less than 0.6×109/L. CD4+T cells in two patients were less than 200×106/L. Four patients had elevated serum cytomegalovirus DNA. The level of β-D-glucan was elevated in four patients. Chest CT showed bilateral diffuse ground glass opacification. PJP-DNA was positive in sputum or bronchoalveolar lavage fluid in all patients. Two patients with type 1 respiratory failure required invasive mechanical ventilation. All patients received trimethoprim-sulfamethoxazole and methylprednisolone treatment. Four patients recovered completely and one died. Conclusion Elderly (aged>55 years) IBD patients who are receiving immune-suppressive therapy or with decreased peripheral blood lymphocyte count are at higher risk of PJP.