Objective: To investigate the influence of infectious complications on the outcome of current standard preoperative chemotherapy followed by surgery for clinical stage II/III esophageal cancer. Background: The impact of postoperative infectious complications on survival after transthoracic esophagectomy remains controversial. Methods: Data from a randomized controlled trial (JCOG9907) were used. Infectious complications were classified into three groups: pneumonia, anastomotic leakage, and others. Univariate and multivariate analyses using the Cox proportional hazard model were performed. Results: Among the 152 analyzed patients, the incidence of pneumonia, leakage, and overall infectious complication were 22 (14%), 21 (14%), and 54 (36%). Overall survival (OS) of patients with any infectious complication was shorter than that of patients without infectious complication [hazard ratio, HR 1.66, 95% confidence interval, CI, (1.02-2.71)] and progression-free survival (PFS) also tended to be shorter in patients with any infectious complication [HR 1.44, (0.92-2.24)]. The OS of patients with pneumonia was shorter than that of patients without pneumonia [HR 1.82, (1.01-3.29)], and PFS also tended to be shorter in patients with pneumonia [HR 1.50, (0.85-2.62)]. The OS of patients with anastomotic leakage (n = 21) was nearly identical to that for patients without leakage [HR 1.06, (0.52-2.13)] and PFS showed the same tendency [HR 1.28, (0.71-2.32)]. Multivariate analysis revealed that pneumonia tended to compromise OS and PFS [HR 1.66, (0.87-3.17) and HR 1.37, (0.75-2.51)]. Conclusions: These results indicate that postoperative infectious complications may worsen patient prognosis after esophagectomy. Performing esophagectomy without postoperative complications, especially pneumonia, may be beneficial for improving survival outcomes.