['Thromboembolism (TE) is a leading cause of death amongst cancer patients. The effect of neoadjuvant chemoradiotherapy (nCRT) on the risk of TE in rectal cancer patients is unknown. The aim of this study was to determine whether nCRT was associated with an increased risk of TE in patients with rectal cancer, either during therapy or with subsequent treatment.', 'This was a retrospective study from a prospectively maintained database at a tertiary referral centre. Participants included patients with rectal cancer treated between January 2000 and December 2013. The primary outcome was the rate of TE in patients with rectal cancer who had nCRT compared with those who did not.', 'One hundred and seventy-one (7.8%) of 2181 rectal cancer patients developed TE. Patients who had nCRT did not have an increased incidence of TE compared with those who had surgery alone (81/946, 8.6% vs 94/1235, 7.6%, P = 0.42) after a median follow-up of 95 months. Ten (1.1%) of 946 patients who received nCRT developed TE during or immediately after nCRT. Most TE events occurred in the 30-day postoperative period (70 patients, 3.2%).'] Is neoadjuvant chemoradiation for rectal cancer associated with higher rates of thromboembolism?