[Show abstract][Hide abstract] ABSTRACT: Resources of water are limited in many agricultural areas of West Asia. Therefore, effective use of this scarce resource is very important in this region. So, this research was conducted in 2009-2010 growing season at Research Farm of Agricultural Researches Center of Khuzestan, Iran, to investigate the effects of two irrigation regime (I1: normal irrigation and I2: no irrigation in post-anthesis growth stage) on grain yield of five wheat cultivars (‘Chamran’, ‘S-78-11’, ‘A’, ‘S-80-18’ and ‘S-82-10’). A split plot experiment based on randomized complete block design in three replications was used, with the irrigation regime in main plots and wheat cultivars in subplots. The results showed that 1000-grain weight, grains per spikelet and grain yield were decreased by water limitation. Despite of their significant differences in 1000-grain weight, spikelets per spike and grains per spike, the grain yield of wheat cultivars was not significantly different. It was resulted by different grain yield reduction of genotypes under different irrigation regimes. Genotypes ‘S-80-18’ and ‘S-78-11’ produced highest yield under normal irrigation and drought stress conditions, respectively. The yield reduction of ‘S-80-18’ genotype was highest under drought stress conditions. ‘S-78-11’ was the most tolerant genotype to water deficit occurrence.