The safety and short-term efficacy of laparoscopic surgery for rectal cancer after preoperative chemoradiotherapy has not been demonstrated. The aim of the randomised Comparison of Open versus laparoscopic surgery for mid and low REctal cancer After Neoadjuvant chemoradiotherapy (COREAN) trial was to compare open surgery with laparoscopic surgery for mid or low rectal cancer after neoadjuvant chemoradiotherapy. Between April 4, 2006, and Aug 26, 2009, patients with cT3N0-2 mid or low rectal cancer without distant metastasis after preoperative chemoradiotherapy were enrolled at three tertiary-referral hospitals. Patients were randomised 1:1 to receive either open surgery (n=170) or laparoscopic surgery (n=170), stratified according to sex and preoperative chemotherapy regimen. Short-term outcomes assessed were involvement of the circumferential resection margin, macroscopic quality of the total mesorectal excision specimen, number of harvested lymph nodes, recovery of bowel function, perioperative morbidity, postoperative pain, and quality of life. Analyses were based on the intention-to-treat population. Patients continue to be followed up for the primary outcome (3-year disease-free survival). This study is registered with ClinicalTrials.gov, number NCT00470951. Two patients (1.2%) in the laparoscopic group were converted to open surgery, but were included in the laparoscopic group for analyses. Estimated blood loss was less in the laparoscopic group than in the open group (median 217.5 mL [150.0-400.0] in the open group vs 200.0 mL [100.0-300.0] in the laparoscopic group, p=0.006), although surgery time was longer in the laparoscopic group (mean 244.9 min [SD 75.4] vs 197.0 min [62.9], p<0.0001). Involvement of the circumferential resection margin, macroscopic quality of the total mesorectal excision specimen, number of harvested lymph nodes, and perioperative morbidity did not differ between the two groups. The laparoscopic surgery group showed earlier recovery of bowel function than the open surgery group (time to pass first flatus, median 38.5 h [23.0-53.0] vs 60.0 h [43.0-73.0], p<0.0001; time to resume a normal diet, 85.0 h [66.0-95.0] vs 93.0 h [86.0-121.0], p<0.0001; time to first defecation, 96.5 h [70.0-125.0] vs 123 h [94.0-156.0], p<0.0001). The total amount of morphine used was less in the laparoscopic group than in the open group (median 107.2 mg [80.0-150.0] vs 156.9 mg [117.0-185.2], p<0.0001). 3 months after proctectomy or ileostomy takedown, the laparoscopic group showed better physical functioning score than the open group (0.501 [n=122] vs -4.970 [n=128], p=0.0073), less fatigue (-5.659 [n=122] vs 0.098 [n=129], p=0.0206), and fewer micturition (-2.583 [n=122] vs 4.725 [n=129], p=0.0002), gastrointestinal (-0.400 [n=122] vs 4.331 [n=129], p=0.0102), and defecation problems (0.535 [n=103] vs 5.327 [n=99], p=0.0184) in repeated measures analysis of covariance, adjusted for baseline values. Laparoscopic surgery after preoperative chemoradiotherapy for mid or low rectal cancer is safe and has short-term benefits compared with open surgery; the quality of oncological resection was equivalent. 2010 Elsevier Ltd. All rights reserved.