Sore throat is common after tracheal intubation. Water can be used to lubricate tracheal tubes, but its benefit has not been validated. We thus did a randomised non-inferiority trial to test the hypothesis that a tube lubricated with water does not reduce sore throat after tracheal intubation. We randomized female or male patients (n = 296) undergoing surgery in the ears or eyes to receive either a tube lubricated with water or a tube without lubrication for intubation. We assessed sore throat at 0, 2, 4, and 24 h after surgery; pharyngeal injury at 2 and 24 h after surgery; and respiratory infections within 7 days after surgery. For the incidence of sore throat within 24 h after surgery (primary outcome), the two-sided 90% confidence interval of the risk difference was compared with the prespecified non-inferiority margin of 15%. Other outcomes were analyzed with two-sided superiority tests. The incidence of sore throat within 24 h after surgery was 80/147 (54.4%) in the non-lubricated tube group and 83/149 (55.7%) in the water-lubricated tube group (risk difference -1.3%, 90% confidence interval -10.9% to 8.3%). Because the confidence interval was below the non-inferiority margin, the incidence of sore throat was not higher in the non-lubricated tube group than in the water-lubricated tube group. There was no significant association between groups in the sore throat, pharyngeal injury, and respiratory infection at each assessment time. The tube lubricated with water did not reduce sore throat and pharyngeal injury after tracheal intubation compared to the tube without lubrication.