Objective To investigate the role of miR?193a?3p in the radioresistance of esophageal squamous cell carcinoma ( ESCC) . Methods MTT assay was used to identify the cell lines with the highest radiosensitivity and radioresistance in four esophageal cancer cell lines exposed to irradiation of 6 MV X?ray. Stem?loop quantitative real?time PCR was used to measure the expression levels of miR?193a?3p, miR?155, and miR?22?3P in the two cell lines. Further studies were performed on miR?193a?3p because of the substantial difference in its expression between the two cell lines. The mimic (3PM) and antagomiR (3PA) of miR?193a?3p as well as siRNA ( si?LOXL4) were synthesized and transfected into cells to elevate and inhibit miR?193a?3p expression. MTT assay and flow cytometry were used to evaluate the effects of miR?193a?3p and its downstream gene LOXL4 on radiosensitivity. Results KYSE510 and KYSE410 were characterized as cell lines with the highest radiosensitivity and radioresistance, respectively. miR?193a?3p had a substantially larger difference in expression between the two cell lines than miR?155 or miR?22?3P (1. 00 ∶ 21. 00). Transfection of 3PM resulted in elevated expression of miR?193a?3p in KYSE510, which had a significantly lower radiosensitivity and a significantly reduced apoptosis ratio by 11. 01% compared with the control group ( P<0. 05) . KYSE410 transfected with 3PA had a significantly higher radiosensitivity ( P<0. 05) . The expression of LOXL4, a downstream gene of miR?193a?3p, was negatively correlated with miR?193a?3p expression. Transfection with si?LOXL4 inhibited the expression of LOXL4, which resulted in a significantly lower radiosensitivity and a significantly reduced apoptosis ratio by 7. 07% compared with the control group ( P<0. 05) . Conclusions miR?193a?3p promotes the radioresistance of esophageal cancer cells probably by regulation of LOXL4.