This study was undertaken ta determine the safety af prognostic inflammatory and nutritional index (PINI) as an indicator of metabolic response to surgical stress, and whether there is a relationship between PINI and post-operative morbidity in children. Thirty-two patients who were performed appendectomy were enrolled in the study. Of the pafients 17 had acute appendicitis (Group 1) and 15 had gangrenous or perforated appendicitis (Group 2). Serum albumin (AL), prealbumin (PA), c-reactive protein (CRP) ve alpha-1 acid glicoprotein (AGP) values were measured pre-operatively (-1), on postoperative day 1 (+1), and postoperative day 3 (+3) in all patients. Mean PIN1-1, PINI+1, and PIN1+3 values were calculated by using these parameters. In grup 1, mean PINI-1, PINI+1, and PIN1+3 values were fonud 5.6±3.9, 15.6±7.8, and 5.8±3.6, respectively (p< 0.0001). In group 2, the same values were 25.2±16.4, 47.2±-28.1, and 43.9±24.2, respectively. The difference between PIN1-1 and PINI+1 was found statistically significant (p<0.0001) while there was no significant difference between PIN1+1 and PIN1+3 (p>0.02) in group 2. Mean PINI values were fonud higher in group 2 compared with group 1, and the difference between two groups was statistically significant (p<0.001). These results suggest that PINI is a cafe and valuable index for determination of metabolic response to sur-gical stress in children, and postoperative follow-up of surgical patients.