Platelets play a significant role in cardiovascular diseases. In people with a higher cardiovascular risk, platelets are found in hyperactive and hyperaggregable state. Antiplatelet drugs are often related to resistence and have side effects. Flavonoids are polyphenolic compounds found in plants and exhibit a variety of biological effects, including antiaggregatory effect. French and Asian paradox are examples of the beneficial effect of flavonoids in the prevention of cardiovascular diseases. This thesis studies in vitro antiaggregatory effect of flavanone on aggregation induced with epinephrine. The method used for measurment of antiaggregatory effect was impedance aggregometry and the instrument used was Multiplate® analyzer. Samples of blood were collected from blood-givers who were not on any antiaggregatory therapy and who gave their written and informed consents. Measurements showed a platelet aggregation curve in dependence of time, and area under curve was calculated for every sample. The result was expressed as minimal antiaggregatory concentration (MINaAC), which significantly reduces platelet aggregation. The determined value of MINaAC for flavanone in epinephrine induced platelet aggregation is 0,06 μM. The final result is comparable to existing research papers on antiaggregatory effect of flavanone when aggregation is induced with different inducers. It is possible to assume that with the exception of affecting signal pathways, flavanones exhibit a non-specific mechanism, which includes the stabilization of the platelet membrane. Specific antiaggregatory mechanism of flavanone on epinephrine induced aggregation should be examined. The determined value of MINaAC is achievable through dietary implementations. Possible therapeutical options, drug interactions and altering the laboratory test results should be examined within future research.