The chlorophyll index is used to calculate the total amount of chlorophyll in plants and plays an important role in agriculture. Chlorophyll is the pigment that gives plants their green color. It plays an important role in plant life because it absorbs sunlight, which is converted into sugar and starch through the process of photosynthesis. In other words, by determining the chlorophyll index, one can track the condition of plants, which finds its application in nutrient management throughout the season. The data obtained on the basis of the vegetation index allows planning in agriculture from season to season. The correct evaluation of data is of great value for agriculture, allowing you to increase productivity and yield, and, consequently, profit. The aim of the work was to study the change in the level of the chlorophyll index depending on the phase of development of winter wheat. The object of the study were plants of winter wheat of Moldovan (Moldova 5, Lautar) and Ukrainian (Pysanka) selection, sown on the experimental field of IGFPP with a plot area of 0.024 acre for each variant. The chlorophyll index was measured throughout the growing season using a CM-1000 chlorophyll meter. From the moment of leaving the winter dormancy, there is a sharp increase in the accumulation of chlorophyll, up to the earing stage. This indicator can serve as a criterion for assessing crops after overwintering. From the earing stage to grain growth stage, there is a sharp decrease in the level of chlorophyll, and differences between varieties were observed at this stage of development. This stage allows you to evaluate the energy of the development of varieties. From the stage of milky ripeness to the very death of wheat plants, a gradual decrease in the chlorophyll index was observed. This stage allows you to monitor the rate of maturation of varieties. It has been established that changes in the level of the chlorophyll index do not proceed linearly and largely depend on the genotype, the phase of development of wheat plants and climatic conditions.