Development of stress tolerant cultivars is an objective of many breeding programs,  but success has been limited by inadequate screening techniques, and the lack of genotypes that show clear differences in response to well defined environmental stresses. Thirty four bread wheat landrace genotypes and six improved cultivars ; Sakha 69 , Giza 168 , El-Nelien , Giza 164 , Sids 1 and Gemmeiza 5 were evaluated to stress environments. The objective of this research was to identify wheat landraces having improved adaptation to heat stress. Two field trials were conducted at Kom-ombo Agricultural Experimental Research Station during two successive seasons 1999/2000 and 2000/2001 respectively. Two planting dates ; normal planting (D1=28^th Nov.) and late planting (D2=29^th Dec.) were used to study the effect of terminal heat stress on the yield , yield components , morphological and physiological traits. There was large genetic variability between landraces in their reaction to heat stress tolerance. Wheat genotypes showed different responses to these environments. Delaying sowing date reduced number of days to heading , number of days to physiological maturity , plant height “cm" , biological yield t/ha., grain yield t/ha., number of spikes/^m2 , number of Kernels/spike and 1000-Kernal weight gm with an average of 12.57% , 14.23% , 8.91% , 13.15 % , 45.11% , 16.35 % , 14.85 % and 16.17 % as compared with the optimum sowing date. All genotypes exhibitied higher grain yield under normal sowing date as compared to late planting. In the average , high-yield potential check genotypes Giza 164 , Gemmeiza 5 , El-Nelien , Giza 168, Sids 1 and Sakha 69, as well as four landraces ; LR 38 , LR32 , LR37 and LR36, exhibited significant higher grain yield with low susceptibility index (S) under late planting (heat stress). On the other hand ; the ten top-yielding genotypes under normal planting date conditions included six landraces ; LR5 , LR21 , LR4 , LR38, LR31 and LR1, three Egyptian bread wheat check cultivars ; Giza 164 , Gemmeiza 5 and Sakha 69, and one Sudanese genotypes ; El-Nelian. Genotypes ; LR8 , LR10 , LR16, LR17, LR19, LR29, LR34 and LR37 produced the highest number of spikes/^m2 under both sowing dates. The results indicated that heat stress tolerance could be due to high yield potential and / or low susceptibility index to stress. In general , this study indicates that the value of focusing on landraces as a gene pool to incorporate adaptation to stress environments .