Abstract: Quality of vegetable oils is associated with fatty acid composition. A field study was conducted to determine accumulation of oil and fatty acids of traditional sunflower hybrid during seed development. Seeds were harvested at six times from R6 (reproductive growth stage) to over ripe of seeds. Oil content and thirteen fatty acids were identified as percentage of total fatty acids. As the results, the fatty acid composition and content of oil in crop species were monitored during seed development and affected by environmental conditions. Variations in percentage of miristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), arachidic (C20:0), behenic (C22:0), lignoceric (C24:0) and oil content in different stages of seed development were significant. Oil content had a significant linear increase from the beginning of seed filling to R8 (The back of the head is yellow but the bracts remain green), then showed a slowly increase, reaching a maximum value of 42.31% at fully ripe. Maximum linoleic acid percentage (61.29%) was found at fully ripe while R7 (The back of the head has started to turn a pale yellow) showed the greatest oleic acid accumulation (38.18%). Oil of sunflower seeds had maximum percentage of stearic and palmitic acids during the initial seed filling phase. The highest negative correlation coefficient was noted for oleic and linoleic acids (r:-0.97). The significance of the results lies in the demonstration of the feasibility of seed growth stages at which developing sunflower seed could be modified to change oil and fatty acid contents.