OBJECTIVE To investigate whether mean platelet volume can be used as an inflammatory marker for the diagnosis of acute appendicitis, and to determine the role, if any, of white blood cell count, C-reactive protein and neutrophil count in this regard. METHODS The retrospective study was conducted at Mersin University (MEU) Health Research and Application Center, Emergency Department, Mersin, Turkey, and included medical record of patients having gone appendectomy between April 2012 to July 2013. Based on pathology examination, the cases were grouped as uncomplicated, complicated, and non-appendicitis cases. Preoperative white blood cell, neutrophil, C-reactive protein and mean platelet volume were noted. SPSS 16 was used for statistical analysis. RESULTS Records of 275 patients were studied. Overall, 90(32.7%) patients were uncomplicated, 120(43.7%) complicated, and 65(23.6%) were non-appendicitis cases. The first two groups had a significantly higher white blood cell (p=0.001) and neutrophil (p<0.001) counts than the third one. Mean platelet volume levels were not statistically different (p=0.478).The neutrophil count had a sensitivity of 76.19%, specificity of 56.92%, positive predictive value of 85.11%, and negative predictive value of 42.53%; white blod cell count had sensitivity 68.10%, specificity 61.54%, positive predictive value 85.12%, and negative predictive value 37.38%; mean platelet volume level had sensitivity 74.76%, specificity 35.38%, positive predictive value 78.89%, and negative predictive value 30.26%; and C-reactive protein level had sensitivity 84.29%, specificity 30.77%, positive predictive value 79.73%, and negative predictive value 37.74%. CONCLUSIONS Elevated white blood cell and neutrophil counts may be used as diagnostic tests in cases of acute appendicitis, while C-reactive protein and mean platelet volume levels were not useful as diagnostic markers.