URETERAL OBSTRUCTION damages the kidney roughly in proportion to the degree and duration of obstruction. The length of time that a human kidney will tolerate complete obstruction and still recover useful function is unknown. Thirty-three days is the longest period found in a brief survey of the literature. The following case report indicates that useful function may return as long as 6½ weeks after obstruction. Report of a Case A 48-year-old nulliparous woman had a mesonephric papillary cystadenocareinoma of the left ovary treated by bilateral oophorectomy on Jan. 20, 1961. All of the gross tumor was removed, and she was referred to Roswell Park Memorial Institute for possible further treatment. On admission she had no symptoms except hot flashes. Studies were entirely negative, aside from a 4-cm. mass in the left paracervical area and a nonfunctioning left kidney demonstrated by intravenous pyelography on Feb. 24 (Fig. 1). A laparotomy on March