Introduction: Celiac disease (CD) is a systemic disorder due to gluten in genetically susceptible individuals and characterized by an immune-mediated response. Gluten, triggers a chronic inflammatory response that leads to progressive atrophy of the small intestine in individuals with CD. Mean platelet volume (MPV) is a marker of platelet activation and function, and is considered a marker of inflammation. The objective of our study was to investigate whether MPV values change after introducing a gluten-free diet (GFD) in children with CD. Materials and Methods: The pediatric patients with CD admitted to our pediatric gastroenterology clinic at Konya Training and Research Hospital between November 2013 and May 2016 were enrolled retrospectively. In all of the cases, demographic characteristics complete blood count parameters, including hemoglobin, white blood cell, platelet count, MPV, mean corpuscular volume, neutrophil, lymphocyte, and vitamin B12 values were recorded. The values were evaluated at the time of diagnosis and after six months of a GFD for the children with CD and healthy control subjects. Results: Thirty-three pediatric patients with CD and 44 healthy children with no history of CD in their families or relatives were enrollled. Although the MPV values of patients with CD were slightly higher after a GFD, in the comparison of the values at diagnosis and after a GFD, the difference was not statistically significant (p=0.068). No statistically significant difference was detected between the MPV values of patients with CD at diagnosis and the healthy children (p=0.851). A statistically significant increase was detected in the comparison of hemoglobin, vitamin B12, and MCV values at diagnosis and after a GFD in patients with CD (p<0.001, p=0.002, and p=0.027, respectively). A comparison of the platelet counts at the time of diagnosis and after a GFD revealed a statistically significant decrease (p=0.011). Conclusion: MPV may not be a useful biomarker for monitoring GFD in children with CD.