Background and Aim: Stroke is one of major causes of disability. Therefore, it is important to introduce and develop new treatment approaches in order to improve and enhance post-stroke recovery process for medical, social, and economical purposes. The present study aimed at determining the effect of mirror therapy on walking ability of patients with stroke regarding the muscular power of the affected leg.Materials and Methods: This semi-experimental study was done on 50 stroke patients that were hospitalized in Mashhad Imam Reza and Quaem hospitals. They were randomly classified into two equal groups of control. and mirror therapy(experimental group).For the experimental group, twenty 30 –minute sessions were daily held, so that every. patient did the range of motion of lower extremitiy of the healthy side in front of a mirror and observed just its mirror image. In addition to mirror therapy , the routine program physiotherapy was performed for both groups. Power of muscle in the affected leg was assessed on the basis of a 5-score scale and every patient`s walking ability was assessed before, during, and after intervention using function ambulation classification. Finally, the obtained data was analyzed by means of SPSS software (V:11.5), using independent T, paired T,Mann-Whitney and Wilcoxon statistical tests.Results: The two groups showed no significant difference in terms of walking ability regarding the muscular power of the affected leg and confounding variables before intervention (P=0.210). Walking ability of the affected leg in mirror therapy group did not significantly improve in comparison with the control group after intervention (P=0.756). But the walking ability regarding the muscular power of the affected leg in mirror therapy group was significantly improved in comparison with the control group in the 10th session (P=0.038).Conclusion: Mirror therapy can improve walking ability of patients with stroke as a simple, inexpensive and a patient-oriented treatment.