The present investigation was undertaken to study heterosis and the amount of variations in different sunflower genotypes. A half diallel cross was used among 10 inbred lines of sunflower producing 45 F1 hybrids to evaluate heterosis and genetic information for vegetative, yield and its components. Highly significant differences were obtained among the genotypes which indicated diversity between them. Mean squares due to general (GCA) and specific (SCA) combining abilities were highly significant for all traits. Two parental lines Ha64 and Ha93 displayed the highest general combining ability effects in the desired direction for plant height, husk percentage and oil percentage. In addition, the parental line Sha14 (P7) was good general combiner for head diameter, seed yield/plant, 100-seed weight. Significant heterosis obtained for seed yield/plant was ranged from 30.48 to 218.66% and from -12.44 to 209.92% over the mid-parent and better parent, respectively. The cross Ha64 x Sha13 (P3 x P6) expressed highly significant positive heterosis over the better parent for oil percentage. Also, the additive genetic component D was non-significant for all studied traits. While, the extent of H1 and H2 was highly significant and higher than D indicating that genes showing dominance effects. Highly significant positive genotypic and phenotypic correlation was found between all studied traits expect oil percentage which showed highly significant negative correlation between all studied traits (plant height, head diameter, seed yield/plant and husk percentage).