The health status of dairy cows has deteriorated considerably with the increase in milk yield of cows in recent decades, mainly due to the negative energy balance, which poses a high risk of disease. Fat supplements are intended to improve the energy balance. Recently the supply of cows with individual fatty acids, which also affect health and fertility through the processes of reproduction and the immune system, has become increasingly important. In this B. Sc. Thesis we wanted to present the different effects of individual fatty acids on milk yield, fertility and the health of dairy cows. The most important period for feeding fatty acids is the period of 30 days before calving and 30 days after calving due to high energy needs and due to changes in metabolism and changes in hormone function. Saturated fatty acids, especially palmitic acid, improve milk yield, but deepen the negative energy balance, so the supply of long-chain unsaturated fatty acids, which improve energy utilization and energy balance, is more appropriate during this period. Fatty acids n-3 and n-6 are involved in the synthesis of lipid mediators in reproductive processes and the immune system, and therefore have the greatest impact on fertility and health of cows. Supplying dairy cows with linoleic and arachidonic acid can impair embryo development and insemination performance and increase disease incidence. Feeding n-3 fatty acids (linolenic, docosahexaenoic and eicosapentaenoic acids) is recommended, as they improve fertility and reduce the incidence and severity of disease.