Intraabdominal desmoplastic small round cell tumor (IDSRCT) is a rare tumor with poor prognosis that usually develops in the peritoneal cavity, often in childhood and adolescence. This tumor typically arises as single or multiple masses, and is characterized by diffuse peritoneal implants and the involvement of regional lymph nodes. Because most patients are unable to achieve a complete response with chemotherapy alone, extensive efforts have been made to develop more effective chemotherapy regimens. Here, we report on a case of IDSRCT in a 33-year-old man treated with ifosfamide (IFM)-based chemotherapy. Before treatment initiation, the patient had extensive ascites in the peritoneal cavity and was experiencing abdominal fullness and anorexia. Currently, 8 months after his initial presentation, he is still undergoing chemotherapy and is in good general condition.