The thesis addresses nutrigenomic effects of omega-3 fatty acids and explains how they affect the expression of genes and consequently affect many diseases such as cancer, cardiovascular disease, inflammation and others. Nutrigenomics gives us a deeper understanding of the link between bioactive food components and diseases at the level of molecules and cellular processes. Omega-3 fatty acids are associated with a lower risk for certain types of cancer as they have a cytotoxic effect on cancer cells in which they induce the process of apoptosis or pyroptosis, induce oxidative stress and cause DNA damage. They reduce migration, invasion and proliferation of cancerous cells. When it comes to inflammation, omega-3 fatty acids are involved in resolution of inflammation as they reduce the expression of inflammatory and in the same time increase the expression of anti-inflammatory genes. They also reduce intracellular levels of reactive oxygen species and are precursors of lipid mediators with anti-inflammatory actions, termed eicosanoids. Therefore they help in treatment of inflammation-associated diseases, such as cardiovascular disease, obesity and others.