As a hallmark of platelet activation, mean platelet volume (MPV) has been identified to be associated with various malignancies. However, the correlation between MPV, mean platelet volume/platelet count ratio (MPR), and esophageal squamous cell carcinoma (ESCC) remains unclear. The aim of this study is to clarify the relevance of MPV and MPR in patients with locally advanced ESCC. Four hundred and fifty-seven cases with newly diagnosed locally advanced ESCC followed by radical surgery and 240 healthy subjects matched for age and gender were included in this study. We retrospectively compared various hematological variables between groups and analyzed the correlation between MPV, MPR, and patients’ clinicopathologic characteristics. Preoperative MPV and MPR were found to be significantly decreased in locally advanced ESCC when compared to healthy controls, they were (8.14 ± 1.09 fL vs. 10.23 ± 0.78 fL, P < 0.0001) and (0.03875 ± 0.02645 vs. 0.04463 ± 0.00972, P = 0.001), respectively. In addition, patients with advanced tumor length (≥4 cm) tended to have lower MPV levels (8.03 ± 1.11 fL versus 8.33 ± 1.21 fL, P = 0.005), while there was no difference between other subgroups. Moreover, decreased MPR was significantly correlated with advanced tumor length (P < 0.001) when divided at a median of 0.03420. Decreased MPV and MPR were significantly associated with locally advanced ESCC. Thus, they might be helpful in screening and risk stratification for locally advanced ESCC in combination with other approaches. Sun, Zhao, Wang, Mo, Zhao, Wang, He, , (2017). The clinical implications of mean platelet volume and mean platelet volume/platelet count ratio in locally advanced esophageal squamous cell carcinoma. Diseases of the esophagus : official journal of the International Society for Diseases of the Esophagus, 2017 Oct;():. https://www.ncbi.nlm.nih.gov/pubmed/29077856