Background: Acute appendicitis is an inflammatory disease and acommon cause of acute abdominal pain. The application of the sophisticated automated hematology analyzer more precisely define the morphology changes blood cells. According to this diagnose and treatment control issues are solved by easy and not expensive way. Recent studies haveshown that there is a negative correlation between platelet count (PC) and MPV and that theratio of these two values may be more meaningful. The aim of our study was to investigate thediagnostic value of MPV and the MPV/PC ratio in acute appendicitis. Methods: The patients were divided into two groups based on their histopathological findings: the uncomplicated and complicated appendicitis groups. Leukocyte count, PC, MPV and the MPV/PC ratio were compared all groups. Results: Total of 186 patients, including 119 men, were included in the study. The average age of all patients was 10.21±1.22 years. There was statistically significant difference of some parameters in peripheral blood between the uncomplicated and complicated appendicitis groups in terms of all index. (p<0.001). Leukocyte count had a strong discriminatory property based on the area under curve (AUC) 0.714, (p<0.001). MPV, PC and the MPV/PC ratio had weak discriminatory power with AUC values <0.663. Using receiver operating characteristic (ROC) analysis, the sensitivity and specificity of MPV were 81.56and 45.7%, respectively, and 63.78% and 71.06%, respectively, for the MPV/PC ratio. Conclusions In our study, MPV and the MPV/PC ratio were useful in the diagnosis of acute appendicitis.