The authors examine the various techniques for diagnosing Retroperitoneal Tumours (RPT) and analyse the results of the surgical treatment performed. Between March 1987 and February 1991, 20 patients with RPT (6 benign and 14 malignant forms) were observed in our Institution. CT and NMR revealed more diagnostic accuracy than other techniques (100%), while NMR had greater accuracy than CT in predictly resectability preoperatively (100% vs. 80.0%, respectively). A total of 26 laparotomies were performed: 20 for primary neoplasms and 6 for recurrent tumours. Exeresis of the mass was performed in 18/20 (90%) patients. Mean follow-up was 57.6 months (84-36). The benign forms had no recurrence. In malignant cases the disease recurred in 58.3% of the cases after an interval varying from 10 to 59 months. Overall mean survival of the 12 patients with malignant tumours subjected to resection was 58.3%. The 1- and 3-year survival rates were 91.7% and 58.3% respectively. Prognosis in malignant RPT is still very poor.