1. In a series of 453 patients treated by pelvic lymphadenectomy for carcinoma of the cervix, 131 developed clinically detectable lymphocysts, an incidence of 28.9 per cent. It is obvious from lymphangiographic studies that surgical interruption of the lymphatic channels of the pelvis is the cause of the complication, with both incidence and severity proportional to the degree of injury.2. Depending upon the size of the cyst, compression of the pelvic viscera may produce varying degrees of disability. These pressure effects are readily demonstrable by routine roentgenographic procedures such as intravenous pyelography, barium enema examination, and pelvic venography. Lymphangiography is usually unnecessary, although it has been indispensable in elucidating the cause of lymphocysts.3. Details of the treatment of lymphocysts are discussed and possible methods of prevention are considered.