The effects of growing seasons on the enzymatic activities (alpha amylase and dehydrogenase) of seeds of five sesamum genotypes viz., Uma, Amrit, Nirmal, CUMS-17 and Prachi in six developmental stages (7, 14, 21, 28, 35 and 42 days after anthesis) were investigated. The experiment was conducted in the Department of Seed Science and Technology, Odisha University of Agriculture and Technology (OUAT), Bhubaneswar during 2014-16. The alpha amylase and dehydrogenase activities in the developing seeds increased consistently till 35 days after anthesis (DAA) after which there was slight decrease in values of these traits up to maturity (42 DAA). Among the varieties, Prachi registered the highest alpha amylase activity (140.25 µg/g) followed by CUMS-17 (137.00 µg/g) at physiological maturity stage (35 DAA) and Uma had the lowest value (124.25 µg/g). Among the growing seasons, the kharif seeds had the highest alpha amylase activity (140.75 µg/g) followed by summer (131.50 µg/g) and rabi (122.65 µg/g). Among the sesame varieties studied, the dehydrogenase activity was found to be highest in Prachi and CUMS-17 (0.36 mg/g and 0.33 mg/g) and lowest in Uma (0.28 mg/g). The harvested kharif seeds registered the highest dehydrogenase activity (0.34 mg/g) followed by summer (0.30 mg/g) and rabi (0.29 mg/g) seasons.