The staging of gynecologic cancers requires the knowledge of lymph node status and thus pelvic and/or lumbo-aortic lymphadenectomy remains, to date, a widely used procedure. Lymphoceles are a frequent complication of surgical lymph node dissection. They are lymph collections in the retroperitoneum following the continuous drainage of afferent lymph vessels. To assess the incidence of this complication, its CT features and the role of diagnostic imaging to treat lymphoceles, 140 patients were retrospectively evaluated. Forty of them had undergone pelvic and/or lumbo-aortic lymphadenectomy for proved endometrial carcinoma, 51/140 for proved carcinoma of the cervix uteri, and 49/140 for proved malignant epithelial cancer in the ovary. CT exams were performed during the follow-up, not on a systematic basis but only when a recurrence was clinically suspected (117 cases), or in the presence of surgery and/or irradiation complications (11 cases), or to assess the extent of residual lesion during chemo/radiotherapy (12 cases). Fifty-three lymphoceles were observed in 36 patients: they were monolateral in 18 cases and bilateral in 16; in 34 cases the lymphoceles were found in the iliac space and in 3 cases only in the median perivascular lumbo-aortic space. In the patients with clinically suspected recurrence (117 patients, 27 lymphoceles), lymphoceles were associated with the recurrence in 25 cases, while they were the only CT evidence of a mass in 2 patients. In the cases with clinically suspected complications of former irradiation and surgery (11 patients, 3 lymphoceles), lymphoceles were correctly differentiated from abscesses (2 cases), seroceles (1 case), and hematomas (2 cases). In the group of asymptomatic patients monitored for residual disease (12 patients, 5 lymphoceles), lymphoceles were an occasional finding and, since they caused no complications to the urinary and GI tracts, they were never treated. Four asymptomatic patients only, with no evidence of disease, were submitted to transcutaneous aspiration and drainage under CT-US guidance (1.7 procedures per patient), and lymphoceles resolved in 3/4 cases. The only lymphocele recurring more than once required another laparotomy. In our experience, lymphoceles appear as a common sequela of pelvic lymphadenectomy for gynecologic cancer. CT has proved to be a useful diagnostic tool to assess and characterize the lesions, which must be differentiated from other postoperative complications and from recurring tumors. Lymphoceles needed to treatment in most cases and thus only symptomatic patients, with no cancer, were submitted to aspiration and drainage under CT-US guidance; the maneuver was successful on 75% of cases.