Aim: We aimed to investigate the increase in values of red cell distribution width (RDW) and also the dependence of RDW on leukocyte count (WBC) and C-reactive protein (CRP) values in acute appendicitis (AA).Materials and Methods: This study includes data collected from 407 patients who were admitted between January 2012 and July 2014 to the emergency service and underwent an operation owing to a diagnosis of AA confirmed by a pathology report. These patients were divided into two groups, namely, non-complicated and complicated appendicitis, according to the results of the operation. The control group consisted of 100 adult patients with similar complaints not having acute abdominal conditions. The age, gender, and WBC, RDW, and CRP levels of the patients on admission were recorded retrospectively.Results: A total of 350 (86%) of the patient group were diagnosed with non-complicated appendicitis, 34 (8.4%) with plastron appendicitis, and 23 (5.6%) with perforated appendicitis. No significant difference was observed with respect to WBC, RDW, and CRP levels between the AA groups (p>0.05). The WBC, RDW, and CRP values were found to be significantly different in the AA groups from the control group (p<0.05). The sensitivity and specificity of the WBC, RDW, and CRP values in the AA group were 70% and 60%, 41% and 30%, and 51% and 40%, respectively. No dependence of RDW values on WBC or CRP levels was found.Conclusion: RDW values were found to be significantly higher in the AA group than in the control group. The low sensitivity and specificity values of the RDW test reduce the possibility that it might become a hematologic marker to be used in the definitive diagnosis of AA.