This study was conducted at Research Altyba station where belongs GCSAR during 2007-2008. by using nine parental lines and their 36 F1 hybrids, were obtained from 9x9 half diallel design. The study included stem, earliness and yield component characters, in order to estimate of hetrerosis compare to the mid parents, the better parent and to the standard hybrid, and determine the superior hybrids advantage to invest in agricultural production and benefit from as well as in breeding program development yield of squash. Heterosis over mid parent was evident in all yield components, The hybrid (IL3XIL6) exhibited (16.89 ، 57.57%) respectively for the ratio pistilate flower % and fruit number per plant, negative heterobeltiosis (-13.71%) was recorded by the hybrid (IL3XIL8)for the number of nodes to first flower, While the hybrid (IL3XIL5) showed maximum positive and significant heterobeltiosis (13.06 %) for ratio pistilate flower%, and the hybrid (IL3XIL6) for fruit number per plant (59.47 %) Whereas the results showed that, four hybrids had positive and high significant standard heterosis for plant yield, the hybrid (IL6xIL7) and (IL3XIL6) had maximum value (32.38, 28.68% ) respectively