This study was carried out in El-Gemmieza Agriculture Research Station, Agriculture Research Center, Horticulture Research Institute, El Gharbiah Governorate, Egypt, during two seasons 2020 and 2021. This study aimed to produce a new open field of F₁ squash hybrids under Egyptian conditions using 6 F₁ hybrids obtained from half diallel crosses. The results indicated that analysis of variance revealed highly significant for the mean squares of the parental lines for the studied traits. None of the F₁ hybrids had the highest values for all studied traits. Significant heterosis values versus mid and better parent were detected and showed highly significance for most studied traits. The values of SCA were larger than the corresponding values of GCA adverting pre-dominance of dominance gene effects with respect to most of studied traits. The best combiner parent was showed to have the significant positive magnitudes of GCA effects between P₁ and P₃ for most of studied traits. The best combinations for most of studied traits were observed in the following crosses; P₁ X P₃; P₁ X P₄ and P₃ X P₄, which had the highest values of SCA. Broad sense heritability was higher than their corresponding in narrow sense heritability for all traits. The results showed that the recorded magnitudes of heritability in broad sense ranged from 94.29 to 99.65 % for days to anthesis first female flower and number of leaves / plant, while heritability in narrow sense ranged from 8.20 to 50.10 % for plant length and average fruit weight respectively. From the previous results, it could be recommended that the integration of these parents in genetic enhancement of summer squash programme directing to increase yield and quality traits.