Rising temperatures are proving detrimental for various agricultural crops. Cool-season legumes such as lentil (Lens culunaris Medik.) are sensitive to even small increases in temperature during the reproductive stage, hence the need to explore the available germplasm for heat tolerance as well as its underlying mechanisms. In the present study, a set of 38 core lentil accessions were screened for heat stress tolerance by sowing 2 months later (first week of January; max/min temperature >32/20 degrees C during the reproductive stage) than the recommended date of sowing (first week of November; max/min temperature 35/25 degrees C were highly detrimental for growth and yield in lentil. While HT genotypes tolerated temperatures up to 40/30 degrees C by producing fewer pods, the HS genotypes failed to do so even at 38/28 degrees C. The findings attributed heat tolerance to superior pollen function and higher expression of leaf antioxidants.