In this work, cultivated pea (Pisum sativum L.cv. Master B) is used as a legume model crop plant to investigate the effect of abscisic acid (ABA) treatment on seed filling during embryogenesis. This was evaluated by using two exogenously applied concentrations (10& 20 µM) during three stages of seed developments (early, intermediate and late). Phenotypic characterization of the treated plants included measurement of seed / legume length and diameter at full maturation stages after treatment. The expression of major proteins of the treated plants was detected using SDS-PAGE electrophoresis technique. Our data showed a positive effect of ABA when applied at the late stage of seed development. ABA significantly increased legume size and elevated the expression of some major proteins such as convicilin (70-75 kDa), vicilin (50, 34 kDa) and legumin (40 kDa). The impact of these results is further discussed.