Pneumocystis carinii pneumonia mainly occurs in immunocompromised patients and it is also known of major cause of death in children with acute lymphoblastic leukemia. After consolidation chemotherapy, acute lymphoblastic leukemia children is developed Pneumocystis carinii pneumonia frequently no an opportunistic infection but there were no controlled studies which have been performed to evaluate the usefulness of corticosteroid in Pneumocystis carinii pneumonia with acute lymphoblastic leukemia. We experienced a case of Pneumocystis carinii pneumonia in acute lymphoblastic leukemia with febrile neutropenic 6 years old girl. She was treated with trimethoprim-sulfamethoxazole and prednisone. We report this case with brief review of related literature.