To assess the two most momentous seed’s biochemical characteristics including seed oil content and fatty acid compounds in different winter and spring rapeseed varieties, an experiment was conducted on randomized complete block design with four replications at experimental field of Seed and Plant Improvement Institute, Karaj, Iran in 2005-2007 cropping seasons. 12 varities of rapeseed that involved 5 spring and 7 winter varieties were investigated. The output results showed that there was significant variation among varieties in aspect of fatty acid compounds and seed oil content. In general, spring varieties by seed oil content about 44.35% were superior to winter varieties with 43.14%. Among rapeseed varieties, the spring one ‘Option500’ had the highest seed oil content (45.54%) and the winter variety ‘Talaye’ had the lowest seed oil content (42.15%). In this research, detection of seed oil fatty acid compounds in studied varieties by Gas chromatography revealed that oleic, linoleic, linolenic, palmitic and stearic acid were the main fatty acids in seed oil content of rapeseed varieties. Arachidic, erucic, gadoleic and palmitoleic acid were also portion of fatty acids that detected in insignificant amounts in evaluated varieties. The highest amount of two unsaturated fatty acids namely, oleic and linoleic acid detected in ‘Hyola420’ and ‘Option500’ varieties, respectively. The spring variety ‘Sarigol’ had the highest linolenic acid (9.76%), and the winter varieties ‘Opera’ (4.50%) and ‘Orient’ (4.47%) had the highest level of palmitic acid.
