Two field experiments were carried out during the two successive seasons of 2020/2021 and 2021/2022 at Kaha Vegetable Research Farm, Qaluobia Governorate, Horticulture Research Institute (HRI), Agriculture Research Center (ARC), Egypt. The study aimed to investigate the response of diatomaceous earth applications on yield, quality and pests of cucumber plants were grown under greenhouses conditions. The experimental farm's soil type was clay loam in texture with a pH of 7.98. The cucumber hybrid Sina 1 F1 was used in this study. This experiment included six concentrations of Diatomaceous earth (75% ,50% and 25% as a foliar spray or addition to soil) in addition to control (without foliar spray or addition to soil). During the growth season, plants were sprayed three times, the first time being twenty days after transplanting, the second and third time repeat every two weeks. Results indicate that, the different concentrations application of Diatomaceous earth at the foliar spraying at 75%, addition to soil at 75% and foliar spraying at 50% gave the highest values of plant height and leaf area, highest values of chlorophyll content and increased average fruit weight, early and total yield in both seasons. The same result was observed in the means number of pests associated with vegetative and fruit growth, which recorded the highest decrease throughout the research period.