OBJECTIVE The role of adjuvant radiotherapy in patients with esophageal squamous cell carcinoma (ESCC) remains controversial. This retrospective study was designed to analyze the impact of adjuvant radiotherapy in patients with T3 stage ESCC after radical resection. METHODS Data of a single-center cohort of 692 patients with T3 stage ESCC who underwent radical resection, with or without adjuvant radiotherapy, were reviewed. Univariate and multivariate analyses were performed to compare overall survival (OS) and locoregional recurrence-free survival (LRFS). RESULTS Two hundred and forty-six patients received adjuvant radiotherapy (S + R group), and 446 patients underwent surgery alone (S group). The median survival time and 5-year OS rate were 40.0 months and 40.9 % for the entire population, 50.0 months and 45.6 % for the S + R group and 38.0 months and 38.3 % for the S group (P = 0.114 for S + R group vs. S group). The 5-year LRFS rate for the S + R group was significantly higher than that for S group (50.8 vs. 35.9 %, P < 0.001). In subgroup analyses, adjuvant radiotherapy was found to improve the 5-year OS in the subgroups of tumor length >5 cm, pN0 and pN1 categories, pTNM stage IIa, IIb and IIIa (P < 0.005). CONCLUSIONS Adjuvant radiotherapy is effective in local control of radically resected T3 stage ESCC and may improve the overall survival in certain subgroups, such as the patients with tumor length >5 cm, pN0 and pN1 categories, pTNM stage IIa, IIb and IIIa. Further studies are required to confirm our results.