Patients who undergo cylindrical abdominoperineal resection can have significant complications, especially those who require pelvic reconstruction using myocutaneous flaps. Reconstruction using a biomaterial may be a novel alternative. The purpose of this study is to report the initial results of pelvic reconstruction using human acellular dermal matrix after cylindrical abdominoperineal resection. Between January 2008 and February 2009, pelvic floor reconstruction was performed in 12 consecutive patients who underwent cylindrical abdominoperineal resection for advanced ultralow rectal cancer. Two weeks after the operation, primary complete healing of the perineal wound was seen in 11 patients. At a median follow-up of 8 months, there was no perineal wound breakdown, bulge, or herniation. One patient had an asymptomatic seroma, one patient had a perineal wound infection, and 4 patients had perineal pain that resolved. Human acellular dermal matrix provided a safe alternative for the reconstruction of large pelvic defect in the patients after cylindrical abdominoperineal resection.