Monitoring the depth of anaesthesia is necessary in order to avoid possible consequences of inadequate depth of anaesthesia. Although there is no substitution for an experienced anaesthesiologist who directly monitors patient`s vital functions during surgical procedure, monitoring the value of bispectral index allows evaluation of the depth of anaesthesia, decreases the incidence of awareness, facilitates the dosage of medications and accelerates recovery time including extubation time. The main goal of this thesis was to compare the extubation time in patients whose depth of anaesthesia was monitored by bispectral index (BIS) and patients whose depth of anaesthesia was monitored by clinical signs and vital parameters. The research was conducted at the Department of Pediatric Anesthesiology, Reanimation and Intensive Medicine at the Children's Hospital Zagreb. It was conducted on the sample of 20 children, ages 6 to 12, diagnosed with acute appendicitis and undergone appendectomy. Propofol, fentanyl and rocuronium were used for induction of anaesthesia in both groups. Maintenance of anaesthesia was achieved with a mixture of sevoflurane, oxygen and nitrogen oxide, as well as with the additional application of fentanyl and rocuronium if necessary. The extubation time in a group of children monitored by BIS value was 2,30±0,95 min while in a group of children monitored by clinical and vital paremeters extubation time was 6,30±2,41 min. The values of t-test ( t=4,891; df=11,732) and probability test (p=0,00034) have shown that the difference between groups is statistically significant, with p<0,01.