BACKGROUND: Glucocorticoids modulate the surgical stress response. Previous studies showed that high-dose preoperative glucocorticoids reduce levels of postoperative inflammatory markers and specific biomarkers of liver damage compared with placebo, and suggested a reduced complication rate and shorter hospital stay after liver surgery. However, there are no studies with a clinical primary outcome or of early recovery outcomes. The aim of this study was to investigate whether a single high dose of preoperative glucocorticoid reduces complications in the immediate postoperative phase after liver surgery. METHODS: This was a single-centre, double-blinded, parallel-group RCT investigating preoperative methylprednisolone 10 mg/kg (high dose) versus dexamethasone 8 mg (standard-dose postoperative nausea prophylaxis) in patients scheduled for open liver resection. The primary outcome was number of patients with a complication in the postanaesthesia care unit; secondary outcomes included duration of hospital stay, pain and nausea during admission, and 30-day morbidity. RESULTS: A total of 174 patients (88 in high-dose group, 86 in standard-dose group) were randomized and analysed (mean(s.d.) age 65(12) years, 67.2 per cent men); 31.6 per cent had no serious co-morbidities and 25.3 per cent underwent major liver resection. Complications occurred in the postanaesthesia care unit in 51 patients (58 per cent) in the high-dose group and 58 (67 per cent) in the standard-dose group (risk ratio 0.86, 95 per cent c.i. 0.68 to 1.08; P = 0.213). Median duration of hospital stay was 4 days in both groups (P = 0.160). Thirty-day morbidity and mortality rates were similar in the two groups. CONCLUSION: A high dose of preoperative glucocorticoids did not reduce acute postoperative complications after open liver resection compared with a standard dose. Registration number: NCT03403517 (http://www.clinicaltrials.gov); EudraCT 2017-002652-81 (https://eudract.ema.europa.eu/).