Heat stress due to increased temperature is an agricultural problem in many areas in the world. Transitory or constantly high temperatures cause an array of physiological and biochemical changes in plants such as photosynthesis dark respiration, membrane stability, mitochondrial respiration, and protein denaturation, which affect plant growth and development and may lead to a drastic reduction in economic yield. The development of methods to induce stress tolerance in plants is vital and still receives considerable attention. Approaches taken to develop stress-tolerant plants have included genetic engineering, traditional breeding, in vitro selection, and the use of growth regulators. Polyamines (PAs) such as putrescine (Put) and spermidine (Spd) are small biologically active molecules involved in various physiological processes and play an integral role under different environmental stress conditions. Strawberry ( Fragaria × ananassa ) is an important small fruit in most temperate climate. High temperature is anticipated become limiting factor for strawberry growing as global warming increases in the future. A greenhouse pot experiment was therefore conducted to test whether the application of Put and Spd can mitigate the deleterious effects of high temperature stress on vegetative development in ‘Paros’ strawberry plants. The treatments consisting of temperature at two levels (30 and 40 °C) and three dose of Put and Spd each at 0, 0.5, and 1.0 mM. The layout was as a 2× 5 factorial experiment in a complete randomized design with four replications and two plants per replication. The results showed that applications of Put and Spd significantly decreased injury rating valve in strawberry plants. Increasing temperature caused to decreasing relative water content, and to increasing leaf electrolyte leakage and prolin content in strawberry plant. Application of PAs significantly declined leaf electrolyte leakage, and increased relative water content (RWC) and prolin content in strawberry plant compared with the control. PAs also improved relative leaf chlorophyll (RLC) content and chlorophyll fluorescence ratio, and increased photosynthetic capacity under heat stress condition as compared with the control. Increasing temperature caused to decreasing leafprotein content. Application of PAs significantly increased leaf protein content compared with the control. With increasing temperature, catalase, ascorbate peroxidase, guaiacol peroxidase, and superoxide dismutase activity were increased in strawberry leaves compared to the untreated control. PAs treatment increased enzymes activity in leaves. The highest enzymes activity were obtained from leaves of the plants treated with 1.0 mM Spd. Results showed that significant correlations existed between physiological indices, gas exchange parameters, and antioxidant enzymes activity. These correlations suggested that injury rating valve was negatively correlated with prolin content, RWC, RLC, chlorophyll fluorescence ratio, net photosynthesis, protein content and guaiacol peroxidase activity. Therefore, it could be concluded that PAs ameliorated the negative effects of injury caused by heat stress through preventing decreases in RWC, RLC, chlorophyll fluorescence ratio, net photosynthesis, and protein content. Keywords: Strawberry, Spermidine, Putrescine, High temperatures, Antioxidant enzymes, Physiological parameters and Photosynthetic parameters.