Increasing evidence points out that alcohol intake is a significant risk factor for patient safety at surgery. This review updates the evidence, mechanisms and recommendations. The threshold is relatively low; about two standard drinks per day or more for two weeks prior to surgery double the complication rate. The mechanisms include reduced immune capacity, sub-clinical cardiomyopathy, haemostatic imbalance, delayed wound healing and increased stress response to surgery. These organ dysfunctions are significantly improved or even normalised during total abstinence from alcohol for 1 to 9 weeks. Only two RCTs has been performed to evaluate the effect of intensive alcohol intervention prior to elective surgery. A 70 % reduction of postoperative complications was shown in a meta-analysis. The intervention targeted complete alcohol cessation, with a high success rate. Research on acute surgery is missing. We recommend that patients are given information on alcohol and increased surgical risk, that alcohol history taking is standardised and that evidence-based intervention programs for risk reduction are included in the surgical guidelines in order to improve the patient safety.