Introduction/Objective. Acute appendicitis is one of the most common surgical conditions in children that may be followed by inflammatory postoperative complications. The aim of this study was to determine the association of the preoperative levels of C-reactive protein (CRP) and procalcitonin (PCT) and occurrence of inflammatory postoperative complications in children with appendicitis. Methods. Fifty-four patients were separated into two groups. The first group contained patients with uncomplicated appendicitis (UA) whereas the second group comprised patients with complicated appendicitis (CA). Clinical and laboratory parameters in preoperative period were used for prediction of complications after open appendectomy in children. Results. Patients with CA had significantly higher values of rectal temperature (p < 0.05), longer length of fever (p < 0.001), CRP (p < 0.001), PCT (p < 0.001), longer duration of stay at the intensive care unit (ICU) (p < 0.001), and prolonged hospitalization (p < 0.001) than the UA group. In the CA group, 41.93% had postoperative complications; these patients also had longer duration of fever (p < 0.05), higher level of CRP (p < 0.05), and prolonged hospitalization (p < 0.01) compared to patients in the CA group without complications. Preoperative cut-off values of CRP and PCT (75.8 mg/l and 0.36 ng/ml, respectively) pointed towards higher probability for development of postoperative complications. Rectal temperature and duration of fever had predictive influence in determination of postoperative complications in the CA group. Conclusion. The cut-off values of preoperative levels of CRP and PCT were able to discriminate the subset of patients with higher risk for postoperative complications. Rectal temperature and duration of fever had predictive influence on the occurrence of postoperative complications, while other clinical and laboratory parameters were not able to predict appearance of the complications after open appendectomy in children.