Background: Neoadjuvant chemotherapy (NAC) followed by surgery is a standard treatment for esophageal squamous cell carcinoma (ESCC) in Japan. Efficacy of NAC on the primary tumor is clinically evaluated during NAC and before surgery and is pathologically examined after surgery. Clinical evaluation of the primary tumor is sometimes difficult because primary tumor is nonmesurable lesion and is usually evaluated subjectively, while pathological finding is objective and a gold standard to evaluate efficacy of NAC. In the present study, we tried to evaluate clinicaly efficacy objectively by calcurating tumor volume by esophagography and concordance between volume reduction rate and pathological efficacy. Methods: This retrospective study examined 53 patients who fullfilled the following criteria; (1) thoracic ESCC, (2) underwent resection following NAC between January 2011 and February 2017, and (3) T2-3N0 before surgey. Clinically, volume of the primary tumor was calculated by multiplying length and thickness in the lateral view of esophagography. Pathological efficacy was examined by the proportion of the tumor disappearance of the primary tumor and was classified as Grade 0-1 when degeneration area was < 2/3, Grade 2 when those area was > 2/3 and < 3/3, and Grade 3 when there was no residual tumor. Volume reduction rate calculrated by the difference of pre- and post-NAC was compared by stratifying pathological grade. Results: T2/T3 was 23/30, respectively. Regimen of neoadjuvant chemotherapy was 5-FU/CDDP in 50 patients,docetaxel/5-FU/CDDP in 1,and 5-FU/CDDP and Radiotherapy in 2. Overall volume reduction rate was 58.9% in median (range -127-100%). Pathological response (Grade 0-1/2/3) was 28/18/4, respectively. Median volume reduction rate (range) was 38.5% (-127-100%) in Grade 0-1, 72.2% (21.7-100%) in Grade 2, and 91.1% (75.5-100%) in Grade 3, which was significantly different (p < 0.01). Conclusions: The volume reduction rate of the primary tumor was correlated with pathological efficacy, suggesting that volume reduction rate could be a objective measure to evaluate efficacy of neoadjuvant chemotherapy for ESCC.