Wheat dwarf virus (WDV) is one of the most harmful viruses reported on cereal crops in many countries, including Ukraine (Mishchenko et al., 2021). Yield losses can reach up to 100% (Jones 2021).The goal of our research was to investigate the impact of WDV infection on the redox reaction, biochemical protective reactions and yield in wheat. Methods. Identification of WDV was performed by ELISA and RT-PCR in wheat plants var. Aktor, Matrix (Vinnytsia region), Koloniya, Dagmar (Khmelnytsky region), breading lines D-12-1, D-12-2 (Kyiv region) in Ukraine. Biochemical characteristics were determinated by Kjeldahl method, anthron method, spectrophotometric methods, protein electrophoresis. Data processing was performed using Prism Graph 8 (USA). Results. It is established that the content of proteins, chlorophyll a and b of WDV-infected plants decreased by 32.2%, 74.3%, 63.1%, respectively. Content of sugars, flavonoids increased by 28.9% and 26.6% compared to healthy plants, respectively. It has been shown that WDV caused an increase of hydrogen peroxide content, intensification of lipid peroxidation processes and activation of superoxide dismutase, decrease of some antioxidant enzymes activity (catalase and ascorbate peroxidase). WDV infection caused greater peroxidase activity in varieties Koloniya, Aktor. In Dagmar infected wheat slight decrease of peroxidase activity and increase of glutathione peroxidase activity were revealed. The changes in PR proteins activity (a significant increase in β-1,3-glucanase and chitinase activity in line D-12-1; decrease in chitinase activity by 1.7 times and increased of β-1,3-glucanase activity in line D-12-2) were established. It was found that WDV significantly reduced the number of seeds per spike, the weight of seeds per spike, while weight of 1000 grains was also decreased (Mishchenko et al., 2021, 2022). The obtained results shown that WDV infection causes yield reducing and wheat variety changes in biochemical characteristics associated with the formation of plant defense mechanisms (parameters of ROS-homeostasis, activity of PR proteins). These data will contribute to developing a technique for early diagnosing plant viruses and identification of resilient varieties to viral diseases.