An experiment was carried out between 2007- 2008 in the Dryland Agriculture Research sub- Institute Sararood in order to study the effects of drought stress on yield and yield components of wheat cultivars under field conditions. The experiment was based on split plot in a randomized complete block design with three replications. The main plots included drought stress treatments at 4 levels: I1-drought stress at the start of stem elongation stage (31 of the Zadoks); I2-drought stress at the start of boot stage (43 of the Zadoks); I3-drought stress at the start of grain filling stage (70 of the Zadoks) and I4-full irrigation. The subplots included cultivars treatments at 3 levels: Chamran (C1), Marvdasht(C2) and Shahriar (C3). Compared to the control treatment (I4), treatments (I1), (I2), and (I3) exhibited 85%, 57%, and 43% yield decrease, respectively. In response to moisture stress during different growth stages, Shahriar cv(C3) was damaged more severely than Chamran cv (C1) . Chamran cv (C1) was one of cultivars with high yield potential in moisture stress conditions, especially in terminal season drought stress conditions