Quantitative traits and the response of 20 genotypes of soybean to water deficit stress were evaluated at Agricultural Research Station of Gorgan in 2010 and 2011. Therefore, 3 separate experiments were conducted, each experiment as randomized complete block design, in 3 replications. In the first experiment, all soybean genotypes were irrigated based on 50 mm evaporation from evaporation pan, but in second and third experiments, the irrigations were applied based on 100 and 150 mm evaporation from evaporation pan. In all 3 stress levels, effects of genotype were significant on most of studied traits. Decreasing soil moisture and inducing drought conditions decreased grain yield in studied genotypes, however, the amount of yield reduction were different in genotypes. The mean grain yield of soybean genotypes in non-stress and stress conditions was 1989 and 1242 kg ha^-1, respectively. Genotype HT2 in non-stress conditions (2569 kg ha^-1), PE10 in medium stress conditions (2222 kg ha^-1) and WE6 in high stress conditions (1688 kg ha^-1) had the highest grain yield, respectively, which can be used in research programs.