Background Few prospective studies have been performed about the impact of preoperative radiotherapy (PRT) or total mesorectal excision (TME) on health-related quality of life (HRQL) and sexual functioning in patients with resectable rectal cancer. This report describes the HRQL and sexual functioning of 990 patients who underwent TME and were randomly assigned to short-term PRT (5 × 5 Gy). Patients and Methods The Rotterdam Symptom Check List supplemented with additional items was used with questionnaires before treatment and at 3, 6, 12, 18, and 24 months after surgery. Patients without a recurrence the first 2 years were analyzed (n = 990). Results Few differences were found in HRQL between patients treated with or without PRT. Daily activities were significantly less for PRT patients 3 months postoperatively. Irradiated patients recovered slower from defecation problems than TME-only patients (P = .006). PRT had a negative effect on sexual functioning in males (P = .004) and females (P < .001). Irradiated males had more ejaculation disorders (P = .002), and erectile functioning deteriorated over time (P < .001). PRT had similar effects in patients who underwent a low anterior resection (LAR) versus an abdominoperineal resection (APR). Patients with an APR scored better on the physical (P = .004) and psychologic dimension (P = .007) than LAR patients, but worse on voiding (P = .0007). Conclusion Short-term PRT leads to more sexual dysfunction, slower recovery of bowel function, and impaired daily activity postoperatively. However, this does not seriously affect HRQL. The comparison between LAR and APR patients demonstrates that the existence of a permanent stoma is not the only determinant of HRQL.