Abstract: This study was conducted to determine the general and specific ability, the heterosis, heterobeltiosis for grain yield and some yield components in pea as a good source of plant protein. Grain yield and its inheritance were studied in four pea cultivar and three winter pea genotypes by crossing them in line x tester fashion. The General Combining Ability (GCA) and Specific Combining Ability (SCA) effects were highly significant, indicating the presence of both additive and non-additive type of gene action. The ratio of additive variance to dominance variance indicated the predominant role of non-additive gene action for all traits. Heterosis was determined as the superiority over the mid-parent (HMP) and also over the better parent (HBP). Hybrids generally showed a better yielding than their parental genotypes. Grain yield showed highly significant heterosis: 83.2% heterosis over mid-parent and 66.8% heterosis over better-parent, respectively. An estimate of heritability (narrow sense) was low due to the major role of environmental factors in expression of grain yield and yield components in pea. Thus, delay selection was suggested for breeding of stable yielding lines. Correlation studies showed that the grain yield was significant positive correlated with plant height, pod number, seeds of pod and pod yield. The highest direct effect was exhibited by pod yield, indirect effects, especially through the pod number in the parents and hybrids.