Summary. Fibrinogen is a plasma protein that is highly susceptible to oxidation. Because of this chemical modification, fibrinogen acquires thrombogenic characteristics under different pathophysiological conditions. Increased carbonyl content and reduced porosity impair the degradation of formed fibrin mediated by plasmin. Fibrinogen is capable of interacting with many proteins, ions, and small molecules. These interactions can modify the functions of this protein. The discovery of new binding partners that may protect fibrinogen from harmful oxidation and, thus, preserve its normal function is essential. Some of the newly detected interactions between fibrinogen and small, natural bioactive molecules, together with the influence of these interactions on the structure and function of fibrinogen, will be presented in this text.