The experiment was carried out at station of agriculture research, College of agriculture, Kirkuk University, during the fall growing season (2017/ 2018). To study the genotypic and phenotypic variation in bulb composition of onion .the experiment included eight genotyoes of onion (Bevas sspy, Sinjary, Deralock, Bevas zour, Baashiqy, Kani Komani, Bayasy bevas and Kani Komani (2). The result showed that there was significant between all traits under study at 5% level of Duncan. which were the number of leaves /plant, biological yield , bulb length , diameter and weight, T.S.S.and total yield per plant. the genotype Bevas sspy gave highest number of leaves per plant, biological yield, bulb diameter, bulb weight and un total yield (ton /hectare). the phenotypic were higher in number of leaves per plant, bulb length, T.S.S and total yield. Whoever, the GCV and PCV were higher in number of leaves per plant, bulb length, and total yield. The broad sense heritability was more than 30 % for the number of leaves per plant biological yield and in total yield, the genetic advance take the same result for the traits under the studied.
