Endometriosis affects about 10-20% of premenopausal women but ureteral involvement is an infrequent event occurring only in 0.1-0.4% of cases. Clinical presentation and radiological aspects are non-specific so that preoperative diagnosis is difficult, requiring a high index of suspicion. Intravenous urography is mandatory in all patients with pelvic endometriosis. Between 1995 and 2001, 10 patients with severe endometriosis of the ureter were referred to our center. Bilateral involvement was present in 3 cases. 6 patients showed a significant involvement of other pelvic organs, with subsequent surgical treatment. 1 patient with bilateral ureteral endometriosis was treated by bilateral stenting and medical hormonal therapy, with good results. 2 patients underwent ureteral resection with primary reanastomosis; one of them showed an ureteral relapse 22 months after surgery, with the necessity of a second resection and ureteroneocystostomy. Ureteric resection and ureteroneocystostomy were initially performed in the other 7 patients, without evidence of recurrences in all cases (median follow-up 31 months). Hormonal therapy or hysteroadnexiectomy, when feasible, are necessary to reduce the risks of relapses. In our opinion, ureteral resection associated with ureteroneocystostomy gives the best chances to cure severe ureteral endometriosis.