The anorectal function was evaluated in 25 patients with rectal cancer who underwent a low anterior resection (LAR). The result of anorectal manometry was analyzed with respect to the bowel habit. Patients were examined preoperatively and 3, 6, 9, and 12 months postoperatively by both anorectal manometry and interview. The examinations included information on defecation frequency, incontinence, and inability of deferment. The defecation frequency was significantly increased until 6 months postoperatively (p < 0.05). The maximum resting pressure (MRP) was significantly decreased until 1 year after surgery (p < 0.05). However, the maximum squeezing pressure (MSP) and the length of high pressure zone (HPZ) were not significantly decreased postoperatively. There was no significant difference in the sensation of balloon between the preoperative period and the postoperative period. The sensation of fullness was markedly decreased until 6 months postoperatively (p < 0.05). The rectoanal inhibitory reflex (RAIR) was positive in all patients preoperatively, and 24 out of 25 patients showed a positive reflex postoperatively with various sensitivity. The appearance of an external sphincter assist was not correlated with bowel habit. Patients with the lowest anterior resection (LLAR) had a higher incidence of early phase incontinence than patients with the low anterior resection. In conclusion, the increased defecation frequency during the postoperative period appeared to be related with the decreased MRP and the sensation of fullness based on a manometric assessment. Although the manometric finding did not normalize with respect to every manometric factor evaluated, the bowel habit was generally recovered clinically in 12 months postoperatively. We should always consider other variables, such as postoperative rectal mucositis or respective bowel habit, in addition to the result of anorectal manometry for the postoperative evaluation.