Twenty pearl millet genotypes were grown in two experiments i.e. normal and water stress irrigation during two seasons (2019 and 2020) at Agronomy Dept., Faculty of Agriculture, Assiut University. The variance due to interaction between genotypes x irrigation was significant for all studied traits, except chlorophyll content in 2019 season. Moreover, mean squares due to treatments of irrigation and genotypes were significant for all traits i.e. plant height, number of tillers/plant, leaves/ stems ratio, fresh and dry protein forage yields and chlorophyll content in both seasons, except total protein forage yield in 2019 season, suggesting that all traits were markedly affected by water stress and possessed a wide range of differences among the studied genotypes. Mainly, the water stress caused a decrease in plant height, number of tillers/ plant, leaves/stems ratio, total fresh, dry and protein forage yields and chlorophyll content by 28.1, 47.2, 21.9, 34.0, 20.3, 12.6 and 14.7%, respectively, as average of the two seasons. The used pearl millet genotypes were classified according to drought susceptible index (DSI) into two groups i.e. less than unity, tolerant to drought, and the other large then unity, susceptibility to drought. Some of those genotypes were differed from season to season for reduction and DSI and from trail to another. The superior genotype using DSI were genotypes Nos. 1 and 2 and there were tolerant to drought stress for forage yield. The obtained results could propose the DSI as a good tool to select the most adapted genotypes under water stress condition.