Background and Objective: Cerebrovascular accident (CVA) is a severe debilitating neurological condition in adults. This study sought to assess the effect of observation and mimicking functional activities on weight distribution and dynamic balance index improvement in lower limbs of hemiparetic patients based on mirror neuron theory. Materials and Methods: This clinical trial was performed on 36 males and females aged 45-60 years who suffered ischemic CVA for the first time. Subjects were randomly divided into 3 groups as follows: viewers of functional film, viewers of non-functional (symbol) film and the control group (not watching any film). The physiotherapy treatments in all groups were similar. Results: Weight percentage distribution was not significant. The values prior to and after dynamic balance index were statistically significant in all 3 groups. Significant differences were found between group 1 and the other 2 groups in terms of balance index percentage change (level 6). Conclusion: Observation and imitation of action along with rehabilitation exercises and functional activities had a positive effect on the improvement of balance Index in post-stroke patients. Refrences 1- Geurts AC, de Haart M, van Nes IJ, Duysens J.A review of standing balance recovery from stroke. Gait Posture. 2005 22: 267-81. 2- DE Haart M, Geurts AC, Huidekoper SC, Fasotti L, van Limbeek J. Recovery of standing balance in postacute stroke patients: a rehabilitation cohort study. Arch Phys Med Rehabil. 2004 85: 886-95. 3- Harris JE, Eng JJ, Marigold DS, Tokuno CD, Louis CL. Relationship of balance and mobility to fall incidence in people with chronic stroke. Phys Ther. 2005 85: 150-8. 4- Aminoff MJ, Boller F, Swaab DF. Clinical neurology and stroke. Handbook of Clinical Neurology. 2009 5- Genthon N, Rougier P, Gissot AS, Froger J, Pélissier J, Pérennou D.Contribution of each lower limb to upright standing in stroke patients. Stroke. 2008 39: 1793-9. 6- Pereira LC, Botelho AC, Martins EF. Relationships between body symmetry during weight-bearing and functional reach among chronic hemiparetic patients. Rev Bras Fisioter. 2010 14: 229-66. 7- Chen IC, Cheng PT, Chen CL, Chen SC, Chung CY, Yeh TH.Effects of balance training on hemiplegic stroke patients. Chang Gung Med J. 2002 25: 583-90. 8- Di Fabio RP, Badke MB.Stance duration under sensory conflict conditions in patients with hemiplegia. Arch Phys Med Rehabil. 1991 72: 292-5. 9- Ertelt D, Small S, Solodkin A, et al. Action observation has a positive impact on rehabilitation of motor deficits after stroke. Neuroimage. 2007 36 Suppl 2:T164-73. 10- Jang SH, Kim YH, Cho SH, Lee JH, Park JW, Kwon YH. Cortical reorganization induced by task-oriented training in chronic hemiplegic stroke patients. Neuroreport. 2003, 20 14: 137-41. 11- Byl N, Roderick J, Mohamed O, et al. Effectiveness of sensory and motor rehabilitation of the upper limb following the principles of neuroplasticity: patients stable poststroke. Neurorehabil Neural Repair. 2003 17: 176-91. 12- Nakhostin Ansari N, Naghdi S. Techniques in the treatment of stroke rehabilitation. Tehran:Arjmand Press, 2010. 13- Garrison KA, Aziz-Zadeh L, Wong SW, Liew SL, Winstein CJ. Modulating the motor system by action observation after stroke. Stroke. 2013 44: 2247-53. 14- Sale P, Franceschini M. Action observation and mirror neuron network: a tool for motor stroke rehabilitation. Eur J Phys Rehabil Med. 2012 48: 313-8. 15- Franceschini M, Ceravolo MG, Agosti M, et al. Clinical relevance of action observation in upper-limb stroke rehabilitation: a possible role in recovery of functional dexterity. A randomized clinical trial. Neurorehabil Neural Repair. 2012 26: 456-62. 16- Stefan K, Cohen LG, Duque J, et al. Formation of a motor memory by action observation. J Neurosci. 2005, 12 25: 9339-46. 17- Celnik P, Webster B, Glasser DM, Cohen LG. Effects of action observation on physical training after stroke. Stroke. 2008 39: 1814-20. 18- Holmes P. Evidence from cognitive neuroscience supports action observation as part of an integrated approach to stroke rehabilitation. Man Ther. 2011 16: 40-1. 19- Takeuchi N, Izumi S. Rehabilitation with poststroke motor recovery: a review with a focus on neural plasticity. Stroke Res Treat. 2013 2013: 128641. 20- Hafer-Macko CE, Ryan AS, Ivey FM, Macko RF. Skeletal muscle changes after hemiparetic stroke and potential beneficial effects of exercise intervention strategies. J Rehabil Res Dev. 2008 45: 261-72. 21- Nelles G, Spiekramann G, Jueptner M, et al. Evolution of functional reorganization in hemiplegic stroke: a serial positron emission tomographic activation study. Ann Neurol. 1999 46: 901-9. 22- Van de Port IG, Wood-Dauphinee S, Lindeman E, Kwakkel G. Effects of exercise training programs on walking competency after stroke: a systematic review. Am J Phys Med Rehabil. 2007 86: 935-51. 23- Forrester LW, Wheaton LA, Luft AR. Exercise-mediated locomotor recovery and lower-limb neuroplasticity after stroke. J Rehabil Res Dev. 2008 45: 205-20. 24- Arya KN, Pandian S, Verma R, Garg RK. Movement therapy induced neural reorganization and motor recovery in stroke: a review. J Bodyw Mov Ther. 2011 15: 528-37. 25- Dobkin BH. Training and exercise to drive poststroke recovery. Nat Clin Pract Neurol. 2008 4: 76-85. 26- Lewek MD, Feasel J, Wentz E, Brooks FP Jr, Whitton MC.Use of visual and proprioceptive feedback to improve gait speed and spatiotemporal symmetry following chronic stroke: a case series. Phys Ther. 2012 92: 748-56. 27- Cho K, Lee G.Impaired dynamic balance is associated with falling in post-stroke patients. Tohoku J Exp Med. 2013 230: 233-9. 28- Mansfield A, Danells CJ, Inness E, Mochizuki G, McIlroy WE. Between-limb synchronization for control of standing balance in individuals with stroke. Clin Biomech .2011 26: 312-7. 29- Carver T, Nadeau S, Leroux A. Relation between physical exertion and postural stability in hemiparetic participants secondary to stroke. Gait Posture .2011 33: 615-9. 30- Buccino G, Solodkin A, Small SL.Functions of the mirror neuron system: implications for neurorehabilitation. Cogn Behav Neurol .2006 19: 55-63.