Cardiovascular diseases are the leading cause of death in developed countries. Since platelets are involved in the pathological processes leading to cardiovascular events, the antiplatelet properties of substances of natural origin are increasingly being investigated. It has been shown that flavonoids in concentrations that can be achieved in the blood after eating foods rich in polyphenols can affect platelet aggregation. Propolis and plant species of the Lamiaceae family are rich in polyphenols. Chemical characterization of 21 samples of propolis of various origins and 24 extracts of nine species of the Lamiaceae family (Melissa officinalis, Salvia officinalis, Rosmarinus officinalis, Lavandula angustifolia, Salvia brachyodon, Ocimum basilicum, Origanum vulgare, Calamintha nepeta, Mentha x piperita) was carried out with the aim of identifying and quantifying their biologically active compounds (spectrophotometric methods, HPLC, LC-MS). The antiplatelet effect was investigated by impedance aggregometry in whole blood with the addition of ADP as an inducer of aggregation, and the antioxidant effect by DPPH assay. All tested samples showed a statistically significant decrease in platelet aggregation at micromolar concentrations. A correlation between the content of individual polyphenolic components and the biological effect of the tested samples (antiplatelet and antioxidant effect) has been demonstrated.