Purpose: Static balance decrease with aging. Exercise program has significant effects on improving balance. However, the most effective method on improving balance in elderly remains undiscovered. Therefore, the present study investigated the effect of training on the stable and unstable surfaces on the static balance in elderly. 
Methods: This was a clinical randomized trial with a pre-test post-test design. A total of 75 elderly women were studied. The samples were assigned into 4 different exercise groups and a control group. Biodex Balance equilibrium was used to record static balance and Berg Balance Scale (BBS) was applied to record functional balance. Data were analyzed using one-way Analysis of Variance at the significance level of P<0.05.
Results: The total balance, anterior-posterior and medio-lateral balance scores significantly decreased in the training groups after performing the exercise program (P=0.00). After conducting the exercise program, balance scores differently decreased in different groups (P<0.01).
Conclusion: The exercise program improved the BBS, total balance, anterior-posterior, and mediolateral balance scores in the elderly subjects. The proprioceptive system function decreases with aging; thus, exercising on an unstable surface can challenge the proprioceptive system and increase proprioceptive function in elderly. The obtained results revealed that exercising on foam and sand improve the function of this system, due to the involvement of proprioceptive system. Thus, the increased involvement of proprioceptive system in balance, may improve balance on unstable surfaces, compared to hard ones.