Abstract: The aim of this study was (I) to investigate the response of three lentil cultivars [FLIP 86-16 L (large seeds), FLIP 89-31 L (small seeds) and FLIP 95-3L (small seeds ] to osmotic stress (-0.33, -0.66, -0.99 and -1.72 Mpa) during germination and seedling growth, (ii) to identify characters that can be used for screening genotypes, (iii) to determine the effects of cultivars on yield and yield components of rainfed lentil in arid (150 mm rainfall) and semiarid (364 mm) regions. Large seed cultivars had higher percentage germination and germination speed under moisture stress than small seed cultivars, but germination speed was more sensitive to change the osmotic potential than percentage germination. Root and shoot weights of all cultivars were reduced when osmotic potential was decreased, but the extent of reduction in root growth was less than that for shoots. Lentil plants at the semi-arid location (Houfa) had higher seed yield (kg ha-1), 1000 seed weight (g) and plant height (cm), than those grown at the arid location (JUST). Lentil plants from larger seeds cultivar had higher seed yield, 1000 seed weight and plant height than those from smaller seeds cultivars.