The subproject was designed with the aim to explore the possible role of the active components of Thymus serpyllum L. and Urtica dioica L. from Serbia in the prevention and treatment of cardiovascular diseases. In this subproject, the in vivo effects of extracts of Thymus serpyllum L. and Urtica dioica L. on blood pressure, peripheral circulation resistance, lipid peroxidation, and oxidative stress were studied in the model of essential and malignant hypertension in rats with congenital hypertension. These results formed the basis for further research into the chronic effects of biologically active substances from Thymus serpyllum L. and Urtica dioica L. and for their application as dietary supplements in the therapy of cardiovascular diseases.