Apart from the anti-inflammatory action, aspirin (ASA) by inhibiting thromboxane A2 synthesis, decreases platelets activity and possesses the antithrombotic action. However, an ASA effect on fibrinolysis has not been yet finally established. Menon [Lancet 1 (1970) 364] reported increased fibrinolytic response in patients treated with high doses of ASA and this observation started a series of studies to find the relation between aspirin and fibrinolysis. This review comprises the results of those studies, divided into in vitro and in vivo, animal and human experiments. The results of our animal studies are also included. Data survey shows that the ASA effect on fibrinolysis depends on experimental conditions, the dose and the time of drug administration. The results of our study indicate the essential role of plasma components in the fibrinolysis regulation by ASA.