In Egypt, okra is one of the most common summer vegetable crops. High temperature is affecting significantly on okra growth, yield and fruit quality. The purpose of this study was to examine the genetic diversity of fifteen okra cultivars grown at three different planting dates. The experiment was designed in a randomized complete block with spilt plot, incorporated three replications. In the 2018 and 2019 seasons, seeds of okra cultivars were planted on 1^st March (normal), 1^st April (slightly late) and 1^st May (late). The results revealed that planting dates had a significant impact on growth and yield characteristics.  All of the growth, yield, and yield components studied traits, i.e., plant height, number of branches, number of pods per plant, fresh pod weight, total pod yield, as well as physiological trait, chlorophyll content index, were significantly reduced by late planting date on May 1^st, which had extreme high temperature (> 46^oC). While relative cell injury (RCI%) increased significantly. The current study's findings indicate that relative cell injury (RCI%) could be used as an effective selection criteria for selecting the cultivars with lower value of (RCI%). Also,  supports the hypotheses since some okra cultivars i.e., Qena-1, Qena-2, Luxor, Qena-3 and Aswan have outstanding performance in high-temperature environments.