Water stress is one of the most significant abiotic stress factors that leads to the loss of soybean production worldwide. The objective of this study was to quantify the water stress effects on two indeterminate type soybean varieties, Sinara (Sn) and Sigalia (Sg). Two water treatments were used: unlimited watering and 50% water withdrawal compared to optimal one. The experiment was set up in a modified evapotranspirometer. Seed yield, total dry matter, number of pods and seeds were measured during the harvest. Our results showed that water depletion significantly reduced the examined crop yield components. However, the varieties did not always react the same way to the lack of water: Sn produced higher yield with optimal water supply, while Sg produced higher number of pods and seeds.