Sunflower is one of the most widely cultivated oil crops. It produces seeds which have abundant health benefits. Theobjective of this research was to determine the effects of two growing years and five planting dates on agronomic traits and chemicalcompositions in sunflower accessions. In this study, genotype by year interaction was significant for days to flowering, weight of seedsper plant, oil, palmitic acid, stearic acid, oleic acid, linoleic acid, all tocopherol and phytosterol components. The major source ofvariation in most agronomic traits and chemical compositions in sunflower was attributed by variation among genotypes. Days toflowering, head length, and weight of seeds per plant decreased when planting date was delayed. Oil content, stearic acid, oleic acid, α-tocopherol, total tocopherol, β-sitosterol, and total sterol contents decreased but linoleic acid increased when planting date wasdelayed. From this study, valuable information will be provided for sunflower breeders and growers in developing and producingfunctional food resources and products.