The inbreeding strategy for five successive seasons began from 2014 to 2017 at Gemmezia Experiment Station, Gharbya governorate was conducted. Seventeen promising squash inbred lines were selected. The selection focused on plant length, number of female flowers, and the average fruit weight. The coefficient of variance (C.V. %) values showed that most of the lines were highly homogeneous. The inbreeding did not cause depression on most studied traits. All the seventeen developed inbred lines and commercial hybrid F1 Sama (control) were evaluated for the most important characteristics during the two seasons 2017 and 2018 under the open field conditions. Significant differences were observed among all evaluated genotypes in all studied characteristics. The highest values were found in S 36 A for plant length, number of leaves/plant, number of days to the first female flower, and number of female flowers. Among the seventeen lines, S 35, S 27 B, and S 36 A gave the highest values for fruit characteristics and yield components. Also, the previous three promising lines gave the highest early and total yield. These inbred lines are potentially promising as a good source for developing new hybrids characterized by outstanding yield quantity and quality.