Water shortage is one of the most serious challenges in crop production particularly under current climatic change. The study aims to compare the performance of 16 barley genotypes under three irrigation treatments to identify the drought tolerant and sensitive genotypes. In addition, to study the genetic variability and heritability of the major agronomic traits under water deficit and normal irrigation conditions. Two field experiments were carried out at Kafr El-Hamam Research Station, Zagazig, Agricultural Research Center during winter sowing seasons of 2014-2015 and 2015-2016. Three irrigation treatments were used; irrigation once at sowing (T1), twice at sowing and 30 days later (T2) and thrice at sowing, 30 and 60 days after sowing, respectively (T3), using surface irrigation. All investigated traits were affected significantly by irrigation treatments. The genotypes G6, G8, G9, G10, G11, G12, G14 and G15 displayed the highest grain yield and its components at all irrigation treatments. Furthermore, four drought tolerance indices were calculated based on grain yield under stress and non-stress conditions, i.e., mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI) and yield index (YI). It was found that G10 exhibited the highest values in the four indices followed by G14, G9, G8 and G13. On the other hand, the lowest value was presented by G4 followed by G1, G7 and G3. The cluster analysis classified the genotypes based on the tolerance indices into four groups. The first group (A) presented G10, which had the highest tolerance indices and it was considered as highly drought tolerant genotype. Moreover, group B presented G8, G9, G11 and G14 had relatively high values of tolerance indices. Otherwise, group C which presented ten genotypes had intermediate values of the estimated indices. While, group D displayed G4 which had the lowest value and it was considered drought-sensitive genotype. The highest phenotypic (PCV) and genotypic (GCV) coefficient of variation values were assigned for number of spikes/m², grain number/spike and 1000-grain weight. The difference between PCV and GCV values was very low for days to heading and days to maturity and was intermediate for biological, grain, straw yields and plant height while it was relatively high for  number of spikes/m², grain number/spike and 1000-grain weight. The heritability in broad sense was very high for each of days to heading, days to maturity, plant height and 1000-grain weight and was moderately high for the remaining traits under both conditions.