Ureteral endometriosis is a rare yet important entity that can lead to renal failure due to silent obstruction of the ureter. Awareness of clinical and morphologic features can help in early detection and treatment. We analyzed the clinical, pathologic, and immunohistochemical findings of 7 cases of ureteral endometriosis. Mean age of patients was 51 years. All patients presented with hydroureter, accompanied in the most cases by hydronephrosis. Superimposed pyelonephritis was experienced by 2 of 7 patients. Most patients (4 of 7) had previously undergone total abdominal hysterectomy with bilateral salpingo-oophorectomy. In 6 of 7 cases, endometriosis involved the left ureter. The distal one third of the ureter was involved in 6 cases, whereas the middle third was involved in 1 case. In 4 cases, endometriosis was located extrinsic to the ureter, whereas in 3 cases, the ureter showed intrinsic involvement by endometriosis. One case showed simple endometrial hyperplasia. Surgical management included nephrectomy in 2 cases, distal ureterectomy with reimplantation in 3 cases, ureteral stent placement followed by ureteroureterostomy in 1 case, and relief of ureteral obstruction by resection of pelvic endometrioma in 1 case. Immunostains for cytokeratin-7 (CK7) and progesterone receptor (PR) were positive in all of the cases, whereas immunostains for estrogen receptor (ER) were positive in 83% of cases and immunostains for CK20 were negative in all cases. CA125 immunostains were positive in 67% of cases. The stromal cells were positive for CD10, ER, and PR immunostaining. Our findings suggest that the diagnosis of ureteral endometriosis is preceded in most cases by hysterectomy and bilateral salpingo-oophorectomy, possibly because of prior symptoms related to adenomyosis or pelvic endometriosis and that ureteral endometriosis has a strong predilection for involvement of the lower third of the left ureter. Ureteral endometriosis should be included in the differential diagnosis of obstructive ureteral lesions in women, particularly those involving the lower third of the left ureter, even in postmenopausal patients. Immunostains for ER, PR, CK7, CA125, and CD10 can be helpful in challenging cases.