BACKGROUND:A possible negative role of pre-operative use of antitumour necrosis factor-alpha (anti-TNF-α) agents on post-operative outcomes in Crohn's disease (CD) patients is still debated. AIM:To examine the impact of pre-operative anti-TNF-α agents on post-operative outcomes 30 and 60 days after CD surgery in a nationwide Danish cohort. Outcomes were death, reoperation, anastomosis leakage, intra-abdominal abscess and bacteraemia. METHODS:We identified all patients having surgical procedures from 1 January 2000 to 31 December 2010 (n = 2293). Patients were classified according to use of anti-TNF-α agents within 12 weeks before surgery (exposed) or not (unexposed). Outcomes were obtained from nationwide registries and a bacteraemia registry. Sub-analyses were performed for bacteraemia and for impact of pre-operative timing of anti-TNF-α agents. RESULTS:Among surgical procedures for CD, 214 were exposed and 2079 were not. We found no increased relative risks of death or abscess drainage 30 or 60 days after follow-up. Among exposed, 7.5% had a reoperation within 30 days vs. 8.6% among unexposed, adjusted odds ratio (OR) = 0.92, 95% confidence interval (CI): 0.52-1.63. Among exposed, 3.8% had an anastomosis leakage within 30 days after surgery vs. 2.8% among unexposed, adjusted OR = 1.33, 95% CI: 0.59-3.02. No further cases of anastomosis leakages appeared within 60 days. Sub-analyses indicated no increased risk of bacteraemia after 30 days and no increased risks when anti-TNF-α agents were given ≤14 days before surgery. CONCLUSION:We found no significantly increased relative risks of post-operative complications after use of anti-TNF-α agents either 12 weeks or ≤14 days before surgery for Crohn's disease.