To investigate the tolerability of preoperative hyperfractionated pelvic irradiation on ninety male Wistar rats were used, 30 for sham irradiation (control), 30 underwent conventional pelvic irradiation, and the last 30 underwent hyperfractionated irradiation. During irradiation and follow up period of five weeks, weekly body weights were recorded. At the end of the follow up period animals were sacrificed and their ileal segments were examined histopathologically. Both irradiation groups displayed significant weight loss at 3^rd-5^th weeks of irradiation and at 1^st-3 ^rd weeks of the follow up. Four weeks after the end of irradiation; the weight loss in hyperfractionated group was significantly higher, but conventional groups was similar to the control group. The morphological assessment did not display statistically significant difference between the two irradiation groups. Hyperfractionated schedule, which was 20% higher dose than conventional group was applied with a protracted weight loss period but the morphological structure was similar to conventional group. [Turk J Cancer 2008;38(2):57-61]