Ther reponse of a sunflower (Helianthus annuus L) cultivar E. C. 68415 to moisture stress imposed at different growth stages was studied during the post rainy season of 1983-84 and 1984-85 on a medium deep alflsols at University of Agricultural Sciences. Bangalore. The greatest reduction in seed yield (27.3%) occurred when stress was imposed during late flower­ing phase followed by seed filling (23 5%), vegetative (16 4%) and early flowering phases (14.0%). Seed setting was drastically affected due to moisture stress during flowering and seed filling stages. Moisture stress during late flowering decreased number of filled seeds and the stress during seed filling decreased the test weight of seeds.