To determine the incidence and clinical import of lymphocysts after radical gynecologic surgery including lymphadenectomy, we reviewed the records of 173 patients with cervical cancer and 135 patients with ovarian cancer who were followed up by computed tomography. Lymphocysts were found in 35 (20%) and 43 (32%) of the patients, respectively. Patients with cervical cancer and positive lymph nodes had a significantly higher rate of lymphocyst formation than did those with negative nodes (29% versus 14%, respectively, p less than 0.02). Age, type of lymphadenectomy, volume of fluid furthered by postoperative drains, disease stage, and tumor histology were not related to lymphocyst development. We saw no complications strictly attributable to lymphocysts. The clinical import and treatment possibilities are discussed.