This work was carried out at the Experimental Farm of Faculty of Agriculture, AinShamsUniversity, at Shalakan, in the fall and summer seasons of 2004/2005 and 2005/2006. The aim of this experiment was to study the mutagenesis effect of both gamma irradiation (at doses 10, 20, 30, and 40 kr) and EMS (at concentrations 0.025, 0.05, 0.1, and 0.2 %) on two summer squash cultivars, Eskandarani and Gabla, as an attempt to induce mutations of valuable productivity. Three mutant generations were carried out after treating with the two mutagenesis and the results indicated that in M1 generation the values of most studied traits was decreased at the high doses and high concentrations of gamma-rays and EMS, respectively, compared with control plants. In M2-generation, five types of mutant were selected, these mutants were different from their control plant. In M3-generation, four type mutants, namely early flowering, node position of first pistillate flower, high number of pistillate flower and large fruit selected from the M2-generation, were raised to study their behavior compared to the control plants. The progeny test of these mutants revealed that all the mutants in M3 retained the behavior they show in the M2-generation.These mutants were superior to their control plant in these economic characters.