The role of 5-HT3A receptors in nociceptive processing has been demonstrated in several animal models. However, studies in human volunteers have not been reported except for one recent study suggesting that ondansetron could alleviate propofol-induced nociception. Previous studies demonstrated that patients anaesthetized with sevoflurane have more pain than those anaesthetized with propofol. And we further posit that the difference is due to the nociceptive processing induced by the action of 5-HT3A receptors. In this prospective, randomized, double-blind, placebo-controlled study, we assessed the analgesic action of a 5-HT3A receptor antagonist (tropisetron) in women after gynaecological laparoscopy under general anaesthesia maintained with either sevoflurane or propofol.