Biologically active substances (BAS) are substances that play an important role in the life of organisms. They are involved in various processes, such as metabolism, regulation of growth and development, homeostasis maintenance. We can get natural biological substances from various plants. Such BAS include essential oils, which are essential in the relationship of plants with the environment. The accumulation of essential oils is influenced, among other things, by plant life expectancy. The article considers the dynamics of the accumulation of essential oils and individual components of a perennial peppermint plant by the years of crop cultivation.