Objective: To study clinical significances of survivin expression,a marker of circulating tumor cells(CTC),in peripheral blood of esophagus squamous cell carcinoma(ESCC) patients treated with radiotherapy. Methods: Survivin mRNA expression was determined using nest RT-PCR in pre- and post-radiotherapy blood of 72 esophageal cancer patients with radiotherapy,and its associations with clinicopathological features,radiotherapy response and 2-year progression-free survival (PFS) were further evaluated. Results: The positive expression of survivin mRNA in pre- and post-radiotherapy were 54.2%(39/72) and 38.9%(28/72),respectively,and the difference has not statistical significance (P = 0.066). Furthermore,survivin mRNA expression was associated with lymph metastasis both in pre- and post-radiotherapy (P = 0.012 and P = 0.005,respectively). Survivin expression of post-radiotherapy was associated with poor radiotherapy response (P = 0.030). Kaplan-Meier analysis also showed that survivin mRNA expression predicted adverse 2-year PFS both in pre- and post-radiotherapy(P = 0.023 and P < 0.001). However,Cox proportional hazard models indicated that only post-radiotherapy survivin mRNA expression apart from KPS scores and standard chemotherapy were independent prognostic factors for ESCC. Conclusion: Post-radiotherapy survivin mRNA expression may be an useful biomarker related to poor radiotherapy response and adverse prognosis in ESCC patients treated with radiotherapy.