Cucurbita pepo L., an important member of the Cucurbitaceae family, has a wide genetic diversity in terms of fruit and plant characteristics. The objective of this study was to select genotypes with desirable morphological characteristics and to establish a wide core collection. Selected 200 genotypes were identified in detail using 22 morphological characters. Principal component analysis (PCA) and cluster analysis were used to determine the relationships among these genotypes. As a result of the PCA, eight PC axes explained 63.8% of the cumulation variation, while according to the cluster analysis, the morphological similarity level of the selected 200 genotypes ranged from 0.72 to 22.21, and in the constellation diagram formed, six groups were defined. In addition, correlation results clearly showed the relationships between the morphological parameters. Positive and significant correlations were found between plant growth habit and parameters such as plant branching, degree of branching, stem shoot development, petiole length and thickness, leaf blade area. The information obtained from the correlation analysis was used to improve breeding efficiency and reduce the number of plants selected. According to the results of the study, a high morphological variability was found among the squash genotypes. The diverse traits of summer squash are important for improving its agronomic qualities. The data obtained will guide similar research and support sustainable plant breeding and genetic diversity conservation.