Summer squash (Cucurbitapepo L.) is considered to be one of the most popular vegetable crops grown in Egypt. Thus, this study aimed to examin the gene action for some economical traits using a halfdiallel crosses includingsevenvarieties which generate for all 21 F₁hybrids . This study would determine nature of gene actionand estimateheterosis for all yield and yield component traits. The results revealed that the mean squares of genotypes and its components, are GCA, SCA were highly significant for all studied traits,Highly significant differences were also found among genotypes, parents and hybrids for most of yield and yield componentstraits.These results indicated a wide range of genetic variations among the parental varieties used in this investigation. Parent's vs crosses mean squares were highly significantindicated that the average ofheterosis was significant in all crosses for all yield traits. The mean squares ofparents, crosses and parent's vscrosses were highly significant.Both general and specific combining ability variances were found to be highly significant for most traits . The ratio of σ² GCA / σ² SCA was less than unity for all yield studied traits indicating the the importance of non-additive gene action in the production of squash hybrids.The two parents;Saja and Beyaz seemed to be the best combiners for fruit yield trait .