This investigation was carried out at Sakha Agriculture Research Station. Kafer El-Sheikh, Egypt during during 2013/14 and 2014/15 seasons to evaluate thirteen faba bean promising lines under early (mid- October) and late (mid- November) sowing dates comparing with three commercial cultivars. Each sowing date was conducted in a separate replicated complete blocks experiment and combined analysis was done over both sowing dates and growing seasons to study the effect of genotype x environment interaction on heritability and genetic advance for seed yield and some related traits.  Highly significant mean squares of seasons were detected for all studied traits. Sowing dates and genotypes mean squares were highly significant for all traits tested. Mean squares of sowing date x season interactions were highly significant for chocolate spot reaction, No. of seeds/plant and seed yield /plant. Highly significant mean squares of the interactions between genotypes and seasons were found for chocolate spot, No. of pods and seeds/plant, 100-seed weight and seed yield /plant. The interactions between genotypes and sowing dates were highly significant for maturity date, no. of seeds/plant and seed yield/plant. The highest values of predicted genetic advance were mainly due to high vales of heritability and the latest was coupled with high phenotypic coefficient of variability.