This study investigated annual and monthly glacier mass balances Tuni and Huayna Potosi glaciers in Bolivian Andes by hydrological method. Results suggest that hydrological method is sensitive to meteorological and hydrological data but reliable measurements enable it to carry out frequent and intensive analysis that clarify temporal and spatial glacier mass balances. Sublimation, evaporation, and evapotranspiration were also included and proved to be an important element in the water balance.