In order to study the effect of terminal heat stress on grain yield and yield components of spring bread wheat cultivars, a stripe block design was conducted using randomized complete block design with three replications in 35 Km north-east Ahwaz in 2007-2008 cropping season. The vertical plots included four sowing dates (06 Nov., 06 Dec., 05 Jan. and 04 Feb.) and 20 cultivars (Atrak, Arvand1, S-80-18, Star, Inia66, Bolani, Bayat, Pishtaz, Chamran, Chenab70, Darab, Dez, Roshan, Shoeleh, Kavir, Maroon, Hamoon, Hirman and Vee/Nac) were randomized in horizontal plots. The results showed that sowing date, cultivars and their interaction had significant effects on all measured traits. The highest grain yield (5.949 t/ha) was produced in sowing dates of 06 Dec. and the lowest grain yield (1.690 t/ha) was produced in sowing dates of 04 Feb. Chamran had the highest grain yield and Inia66 had the lowest grain yield. Maximum grain yield (7.039 t/ha) related to Chamran in 06 Dec. and the minimum grain yield (1.219 t/ha) belonged to Falat in 04 Feb.844-849