The present investigation was undertaken to identify the promising heat tolerant lines and to evaluate their heat stress responses. Twenty five spring wheat genotypes were studied in non-stressed (optimum sowing) and stressed (late sowing) environments. The experiments were conducted at Regional Wheat Research Centre, Bangladesh Agricultural Research Institute, Gazipur, during the cropping season of 2009-10. Randomized complete block design was used with three replications. Yield and yield contributing phenological and physiological characters varied among the genotypes under both optimum and late sowing conditions. Ground cover, grain filling duration, canopy temperature at grain filling and biomass production were severely affected by the heat stress leading to low grain yield under late sowing condition. G-12, G-13, G-14, G-18, and G-19 were identified as heat tolerant genotypes based on their relative performance in yield components, grain yield and heat susceptibility indices. Present genotypes are found to be ideal candidates to be used in developing heat tolerant wheat varieties.