Objective To investigate the effect of therapeutic suggestions played to patients through earphones during surgery on postoperative pain and opioid use. Design Blinded randomised controlled study. Setting Tertiary care medical college hospital. Participants 385 of 400 patients consecutively recruited from January to December 2022 who were to undergo surgery for 1-3 hours under general anaesthesia. In the per protocol analysis 191 patients were included in the intervention group and 194 patients in the control group. Intervention The intervention comprised an audiotape of background music and positive suggestions based on hypnotherapeutic principles, which was played repeatedly for 20 minutes followed by 10 minutes of silence to patients through earphones during general anaesthesia. Patients in the control group were assigned to a blank tape. Main outcome measures The main outcome was dose of opioid administered by patient controlled analgesia or nurse controlled analgesia within the first postoperative 24 hours, based on regular evaluation of pain intensity on a numerical rating scale (range 0-10, with higher scores representing more severe pain)