Background: The Apfel simplified risk score includes four risk factors: female sex, non-smoking status, postoperative nausea and vomiting or motion sickness history, and postoperative opioid use. The score is calculated preoperatively, so postoperative opioid use must be predicted. We aimed to determine whether anaesthetists can predict patients' postoperative opioid use and dose. Methods: Specialist anaesthetists from eight hospitals preoperatively predicted opioid use and dose in the post-anaesthesia care unit (PACU) and for the first 24 h postoperatively, which was compared with actual opioid use and dose. Opioid doses were converted to oral morphine equivalents (MEQ). Correlations between predicted and actual opioid use and dose were analysed with Spearman's rho and linear regression. Results: A total of 487 anaesthetist–patient pairs were included. Anaesthetists overpredicted opioid use (398 [82%] predicted vs 251 [52%] actual patients requiring opioids in the PACU; 396 [81%] predicted vs 291 [60%] actual in the first 24 h) (Spearman's rho [95% confidence interval] 0.24 [0.16–0.33], P