Background Henoch-Schonlein purpura is a systemic small-vessel vasculitis that occurs mainly in children. A review of the literature has suggested a correlation between mean platelet volume and several inflammatory disorders. However, to the best of our knowledge, any potential correlation between mean platelet volume and Henoch-Schonlein purpura has not been reported in the literature. Therefore, our study aimed to evaluate the role of mean platelet volume concentrations in patients with Henoch-Schonlein purpura. Methods This study included 97 children with Henoch-Schonlein purpura and 120 healthy individuals as controls. Results Mean platelet volume concentrations were found to be significantly lower in Henoch-Schonlein purpura patients compared with healthy controls (8.1 ± 0.86 vs. 9.4 ± 0.81, P < 0.001). Similarly, significant negative correlations were observed between mean platelet volume and neutrophil count, platelet count and erythrocyte sedimentation rate in patients with Henoch-Schonlein purpura (r=-0.327, P = 0.001; r=-0.419, P < 0.001; r=-0.255, P = 0.012). Interestingly, mean platelet volume was significantly lower in the acute phase compared with the convalescent phase of Henoch-Schonlein purpura patients (7.8 ± 0.86 vs. 8.3 ± 0.77, P = 0.002). A cut-off value for mean platelet volume was 7.85 with area under the curve of 0.726 to identify acute phase vs. convalescent phase in patients with Henoch-Schonlein purpura. Mean platelet volume was independently associated with Henoch-Schonlein purpura in logistic regression analysis (odds ratio = 0.114, 95% confidence interval = 0.053-0.243, P < 0.001). Conclusions Our results suggest that mean platelet volume is inversely associated with disease in patients with Henoch-Schonlein purpura, and mean platelet volume may be a useful marker to identify active disease in Henoch-Schonlein purpura patients.