The present investigation was carried out during 2010 and 2011 seasons to study the effects of inbreeding depression in sunflower. In 2010 season, Giza102 an open-pollinated cultivar of sunflower was planted at Shandaweel Agric. Res. Stn., ARC. 100 plants were selected and selfed. After harvest, 23 S₁ lines which produced enough seed were chosen for evaluation in the next season. In 2011 season, 23 S₁ lines and Giza102 were evaluated in Randomized Complete Block Design (RCBD) experiment with three replicates. Data were recorded on days to 50% flowering, days to maturity, plant height, stalk diameter, head diameter, 100-achene weight, achene yield/plant, achene yield/plot and oil content. Analysis of variance revealed highly significant differences among S₁ lines for all studied traits. Broad sense heritability showed high estimates for all the studied traits. Phenotypic coefficient of variability (P.C.V) for various traits were relatively higher than genotypic coefficient of variability (G.C.V) for the S₁ per se. Oil content was negatively and not significant correlated with head diameter, 100-achene weight, achene yield/plant and achene yield/plot. Achene yield/plot was positively and significant correlated with head diameter, 100-achene weight and yield/plant. The reduction of yield/plot of the S₁ lines was 2.68% of the base pop. Achene yield/plot of 10 S₁ lines per se were significantly or highly significantly fewer than the base pop. Giza102, while 8 S₁ lines per se exceeded significantly or highly significant than the base pop. Giza102. The decrease in oil content due to inbreeding was 2.25%. Most of the S₁ lines were less than the base population. The best ten S₁ lines per se were Nos.1, 7, 11, 14, 15, 16, 17, 18, 20 and 21, which gave the higher oil content and some other desirable character were selected and used as parents to produce the first cycle selection