The aim of the investigation was to determine the relationship among types of anesthesia, cognitive assessment, negative postoperative behavior changes and the level of neurological biomarkers protein S100B. Prospective study was conducted at the University Hospital Split on 64 children (aged 6-13, ASA I-II) undergoing elective adenotonsillectomy. The children were randomized into 2 groups: TIVA (n = 32) and sevoflurane (n = 32). In TIVA group anesthesia was induced with propofol, fentanyl and vecuronium and maintained with continuous infusion of propofol. In sevoflurane group, anesthesia was induced with fentanyl, sevoflurane and vecuronium and maintained with sevoflurane. In all patients, surgery was performed by the same surgeon and anaesthesia was administered by the same anaesthesiologist. Cognitive assessment was conducted with two psychomotor evaluation tests (PsychE): simple reaction time and dual task. Each subject was examined preoperatively, 2 h and 24h after surgery. Evaluation of negative postoperative behavioral changes were performed with the Post Hospitalization Behavior Questionnaire (PHBQ:- 27 items describing six subscales). The PHBQ was filled out by parents at postoperative days 1, 3, 7 and 14, and 6 months after surgery. S100B assays were performed using the electrochemiluminiscence immunoassay “ECLIA”. There were no unambiguous one-way differences between TIVA and sevoflurane group in cognitive function before anaesthesia, 2 hours and 24 hours after anaesthesia. Children had poorer results in simple reaction time after inhalation anaesthesia, while after TIVA, worse results were in dual task. The number of NPOBCs in all six PHBQ subscales at all follow-up time points was statistically significantly smaller in the TIVA group than in group S. The greatest difference was noticed in the separation anxiety subscale, general anxiety, apathy/withdrawal, eating disturbances, aggression towards authority and sleep anxiety. The values of neurological biomarker S100B were significantly increased after general anesthesia with regard to preoperative values, but there were no differences regarding the 2 types of anaesthesia. Based on the results of our research, we preferthe use of total intravenous techniques over inhalation, for adenotonsillectomy in children.