Abstract： Background Retroperitoneal sarcoma is a rare disease with poor prognosis. The aim of this study was to investigate the prognostic factors of the disease.Methods Between January 1988 and December 2003, 132 patients with retroperitoneal sarcoma were surgically treated in our hospital, 79 of them were followed up for 1-122 months (median: 19 months). Their clinicopathological data including tumor size, histological subtype, grade and resection margin status, were studied. The Kaplan-Meier method and log-rank test were used to analyze the disease-specific survival rates after the resection.Results Among the 132 patients, 98 (74.2%) received macroscopic complete resection, 29 (22.0%) incomplete resection, and 5 (3.8%) surgical biopsy. In the 79 patients who were followed up, macroscopic clear resection of retroperitoneal sarcoma (n=49) was associated with a significantly higher survival rate compared with unclear resection (n=30, P＜ 0.001). The median survival period was 31 months (95%C/, 20.09-41.91; actuarial 1-year survival, 85.7%) in the patients with the tumor completely resected and 11 months (95%C/, 6.71-15.29; actuarial 1-year survival, 46.7%) in those with incomplete resection. Patients with high-grade sarcomas had a significantly shorter survival time (n=39;median: 24, 95%C/: 5.71-42.29) than those with low-grade sarcomas (n=40; median: 15; 95%C/: 8.80-21.20; P＜0.01).Moreover, compared with the patients with the tumor sized ＜15 cm in diameter (n=53), the survival rate was lower in those with a sarcoma sized ＞15 cm (n=26). (Median: 12, 95%C/: 8.26-15.74 vs median: 24, 95%C/: 17.25-30.75; P＜0.05). Furthermore, the survival of the patients with liposarcomas (n=29, median: 29, 95%C/: 12.84-45.16),leiomyosarcomas (n=14, median: 11, 95%C/: 6.11-15.89), and others (n=36, median: 22, 95%C/: 14.95-29.05) varied significantly (P＜0.05)Conclusion Completeness of resection, tumor volume, grade, and subtype are prognostic factors of retroperitoneal soft tissue sarcomas.