&NA;Thirty patients undergoing anterior resection of the rectum were randomized for postoperative drainage with either corrugated (N=14) or corrugated plus Shirley sump drain (N=16). Drainage volume per 24 hours was measured, and volume of residual pelvic fluid collection estimated by CT scan on the seventh postoperative day. A mean of 591.9 ±415.2 ml of fluid drained during the first seven postoperative days. There was a significant (P<0.01) increase in 24 hour drainage volume between the fourth and sixth postoperative days. There was no significant difference in drainage volumes between the two drainage methods. Residual pelvic fluid collection (median volume, 16 ml) was detected in 80 percent of patients at one week after operation. While this was larger (24 ml median) for the corrugated only group compared with the corrugated plus sump drain group (11.5 ml median), the difference was not significant. Fluid loss during the first postoperative week (616.6±424.2 ml) was significantly (P<0.05) less when the anastomosis was situated higher than 12 cm (294±192 ml) compared with 6 to 12 cm from the anal margin (496±210 ml), or after coloanal anastomosis (1077±432 ml). Residual pelvic fluid collection was larger after coloanal anastomosis (median, 33 ml; range, 1.5 to 90 ml) compared with 6 to 12 cm (median, 11 ml; range, 0‐124 ml) or higher than 12 cm (median 9 ml; range, 0 to 16 ml) from the anal margin, but the difference was not significant. Drainage after anterior resection is important because large volumes of serosanguineous fluid collect, especially after resection of low tumors. Neither of the drainage methods tested in this study prevented persisting pelvic fluid collection at the seventh postoperative day.