ObjectiveTo evaluate the effects of sevoflurane and propofol on preoperative implicit and explicit memories in general anaesthesia patients of elective surgery. MethodsThe surgical inpatients in Sichuan Provincial People's Hospital were enrolled from December 2013 to May 2014, and were randomly divided into three groups (S, P, M). In Group S, anesthesia was induced and maintained with sevoflurane. In Group P, anesthesia was induced and maintained with propofol. Midazolam was not utilized throughout the whole anaesthesia for the above groups. Patients in Group S and Group P were given a list of test materials to remember and listen before the anesthesia. Within 12 to 36 hours after operation, memory was assessed, based on the Buchner's model applied on the process dissociation procedure (PDP) using a phrases task. The Group M was given the same test materials, and received test with the PDP in 12 to 36 hours before surgery. Value A and value R were used to represent the implicit memory score and the explicit memory score, respectively. ResultsA total of 150 patients were included, and 50 cases were included in each group. During testing, 2 cases were excluded, 3 cases were loss to follow-up, so finally 49 cases were included in the Group S, 47 cases in the Group P and 49 cases in the Group M. The results showed that there were significant differences in the implicit memory score (A) and the explicit memory score (R) among the three groups (all P values <0.05). The explicit memory score (R) of the Group M was higher than those of the Group P and Group S (all P values <0.05), the implicit memory score (A) in the Group M was higher than those of the Group S and Group P (all P values <0.05), and the implicit memory score (A) in the Group S was higher than that of the Group P (P<0.05). ConclusionPropofol and sevoflurane can decrease the score of explicit memory after anesthesia within 12 to 36 hours, and there are no significant differences in explicit memory between the two drugs. Both propofol and sevoflurane can decrease the score of implicit memory, but the influence of sevoflurane on the implicit memory is less than propofol within 12 to 36 hours.