In order to investigate the effect of different Water Deficiency levels on grain yield and some physiological characteristics of lentil cultivars, a pot experiment carried out as complete randomized block design with four replications at Faculty of Agriculture and Natural Resources, Razi University, Kermanshah in 2011. Experimental factors were include, water deficiency in two levels (control: without water deficiency, water deficiency during vegetative and reproductive growth stages from at -1.2 MPa) and four lentil cultivars (Landrace, Gachsaran, Kimia and Qazvin). Results showed that water deficiency had significant effect on grain yield, RWC, stomatal resistance, proline and chlorophyll fluorescence. Highest grain yield obtained in Gachsaran cultivar in control while in drought treatments landrace cultivar had upmost grain yield also this cultivar showed highest RWC, Fv/Fm, proline and least stomatal resistance.
