The main goal of this work was to determine the binding equilibrium constants of dipyridamole and warfarin to human serum albumin (HSA). A good understanding of blood plasma protein's drug binding properties, especially of HSA's which is the most abundant among them, is of great importance for the prediction of the pharmacokinetic properties of drugs bound by it. Since only the free fraction of the drug can be pharmacologically active, the drug's effect is greatly dependent on its binding properties and because of that the drug's competition for the protein's binding sites can be a cause of drug interactions. The method used in this work to study HSA's drug binding is called fluorescence polarization. It is based upon the property of small fluorescent molecules, such as dipyridamole, to rotate at great speed when unbound and because of that to reduce fluorescence polarization. By binding to a larger molecule, in this case HSA, dipyridamole's rotation speed is greatly reduced, and fluorescence polarization is increased. With the addition of warfarin, dipyridamole's binding site competitor, dipyridamole is released from HSA allowing it to rotate at great speed once again and reduce fluorescence polarization. By measuring fluorescence polarization, it was possible to quantify the bound fraction of dipyridamole and to calculate the binding equilibrium constants based on the measurements obtained first by a titration of a dipyridamole solution with a HSA solution and then by a titration of both dipyridamole and HSA solution with a warfarin solution. The calculations were performed in SPECFIT and two binding models were considered. It was shown that the model in which HSA has two binding sites for dipyridamole better describes the experimental data and that fluorescence polarization is a convenient method for studying HSA's drug binding properties.