Ten parental lines were crossed in a line x tester (7L x 3T) mating design in the summer season of 2016 to obtain 21 F₁ hybrids to study the genetic behavior of some economic traits for cultivars of summer squash crop suitable for Egyptian cultivation.  In 2017 summer season, the ten parents and their 21 F₁ hybrids were evaluated with four commercial checks "Aziad, Adronto, Marselia and Tabark" in the experimental design which was a randomized complete blocks with three replications at Kaha Research Farm of Vegetables Breeding Department, Horticultural Research Institute, (HRI), Agric. Res. Center (ARC) in the Kalyobiya Governorate. Data indicated that fifteen and ten crosses had highly significant values of heterosis over the mid-parents and the better parents, respectively for number of fruits/plant trrait. Concerning heterosis over the checks hybrids, four and two crosses showed significant and highly significant values of heterosis over hybrid Aziad and Tabark, respectively but only one crosses (P₇xP₁₀) showed highly significant positive values over the checks cultivars Adronto and Marselia. Meanwhile, all crosses showed insignificant values of heterosis over the mid-parents and the better parent concerning yield /plant trait. Heterosis over the checks hybrids, three, zero, once and once crosses gave significant or highly significant positive values of heterosis over Aziad, Adronto, Marselia and Tabark, respectively. Two lines and two testers gave significant or highly significant positive values of gca effects on number of fruits/plant trait. Also, three lines showed significant or highly significant positive values of gca effects on yield /plant trait. Therefore, these lines considered good combiners for yield traits. In concern of sca effects, three crosses out of twenty ones gave significant or highly significant positive values for total yield plant trait.