BACKGROUND: Retroperitoneal sarcomas are rare mesenchymal neoplasms. Analysis of their characteristics and their impact upon a particular patient population is of significant importance to the surgeon. From 1970 to 1994, 63 adult patients underwent resection of primary retroperitoneal sarcomas at the University of Florida. STUDY DESIGN: A retrospective analysis was performed to determine the biologic behavior of these tumors, surgical management of primary and recurrent disease, predictive variables influencing survival, and the effect of multimodality therapy. RESULTS: There were 39 females and 24 males and the mean age was 55 years. The median weight of the tumors was 1,815 g (range, 25 to 10,800 g). There were 33 percent leiomyosarcomas, 30 percent malignant fibrous histiocytomas, and 22 percent liposcaromas. Low- grade tumors accounted for 46 percent of the total, and grade was a significant predictor of survival (p=0.002). Seventy-eight percent of the lesions were totally resected, and this clearly influenced outcome (p<0.0001). In 75 percent of cases, adjacent organs were resected concurrently, and 34 percent of the tumors involved local vascular structures. Survival was enhanced by multiple resections in the 40 percent of patients who had a recurrence (p=0.0001). None of the adjuvant therapy regimens demonstrated survival advantage. Thirty-one percent of the study group patients were alive and 21 percent were disease free at the conclusion of the study. Median survival has been 41 months after total resection, nine months after debulking, and five months after biopsy only. CONCLUSIONS: Complete resection and low grade continue to be the most important prognostic factors for this tumor. The survival advantage of multiple resections has seldom been noted end justifies an aggressive surgical follow-up.