BACKGROUND: Intraabdominal desmoplastic small round cell tumors (IDSRCT) are uncommon but aggressive tumors that occur in young males. To the authors' knowledge, only limited data are available on the natural history and optimal treatment of this disease. METHODS: The authors reviewed 12 patients with IDSRCT who were treated at their institution between January 1991 and December 2001. RESULTS: All patients were males, with a median age of 26 years. All patients were symptomatic at the time of presentation, with a mean duration of symptoms of 2 months. Common presenting symptoms and signs were abdominal pain (67% of patients), palpable abdominal mass (58% of patients), abdominal distension (42% of patients), and hepatomegaly (33% of patients). Six patients (50%) had distant metastases at presentation. Five patients underwent biopsy only. Surgical resection was attempted in seven patients and included macroscopic total resection in three patients and debulking in four patients. All of those patients subsequently developed recurrent or progressive disease, which required a second operation in six patients. Overall, 6 patients (50%) developed symptomatic intestinal obstruction requiring surgical management, and 3 patients (25%) developed ureteral obstruction. All 12 patients received multiagent chemotherapy. Seven patients (55%) also received radiation therapy. The median survival of patients who underwent surgical resection was 34 months, whereas the median survival of patients who underwent biopsy alone was 14 months. One patient remained alive 72 months after he underwent complete resection of primary and recurrent tumors, and 1 patient remained alive with disease 32 months after he underwent complete resection of a primary tumor. CONCLUSIONS: Patients with IDSRCT presented with a short duration of nonspecific symptoms, and the disease was fatal almost uniformly, regardless of the treatment modality used. Surgical resection may prolong survival in some patients.