Objective Maintaining balance is one of the most important functions of neuromuscular system in performing all simple and complex¬ sports activities. Musculoskeletal deformities especially, genu varum in the lower extremity, can negatively affect the body’s biomechanics. The aim of this study was to the compare the balance of male athletes aged 11-14 years with and without genu varum. 
Methods This study has a causal-comparative design. From a total of 580 amateur adolescent male athletes in basketball, handball and volleyball living in Marivan County, who had training three sessions per week, 21 with genu varum (Mean±SD of age=13.15±1.22 years; Mean±SD of height=1.68±2.32 cm; Mean±SD of weight=51.23±4.48 kg) and 21 with no genu varum (Mean±SD of age=12.95±1.17 years; Mean±SD of height=1.67±1.45 cm; Mean±SD of weight=49.49±3.48 kg) were recruited. Their genu varum deformity was assessed using a caliper. Static and dynamic balance was evaluated by Bass Stick test and Y Balance test, respectively. Data analysis was performed using independent samples t-test.
Results There was no significant difference in static balance between those with and without genu varum (P=0.61), while their dynamic balance was significantly different in posteromedial (P=0.003) and posterolateral (P=0.004) directions. 
Conclusion Negative effect of knee deformity on balance are turned out over time. Preventive measures and appropriate exercises at an early age may reduce the negative effects of deformities on balance.