Objective: Studies show that developmental stuttering (DS) may be associated with inflammatory processes. Complete blood count (CBC) values have been used as indicators of a systemic inflammatory response. We aimed to evaluate the relationship between CBC values particularly basophil, platelet, and lymphocyte-related parameters and DS. Method: In this retrospective case-control study, the CBC values of 54 patients who were diagnosed with DS were compared with the data of 54 healthy subjects. Results: Basophil count, percentage of basophil, and platelet count were significantly higher (p=0.001, r=0.35; p=0.044, r=0.19; p=0.045, r=0.11; respectively); mean platelet volume was significantly lower in the patient group (p=0.000, r=-0.54). The areas under the ROC curve of basophil count, percentage of basophil, and platelet count for patient group were 0.708, 0.611, and 0.636. A signifi-cant correlation was found between basophil count and platelet count (r=0.276, p=0.048), basophil count and mean platelet volume (r=-0.420, p=0.002), basophil count and percentage of basophil (r=0.685, p=0.000). Basophil count correlated with disease duration (r=-0.296, p=0.035). According to the Binary logistic regression analysis, low mean platelet volume predicts DS. Discussion: Inflammation might play a role in the etiopathogenesis of DS. Basophil and platelet-related parameters may be potential markers for DS. [Anadolu Psikiyatri Derg 2020; 21(2.000): 187-194]