Fibrinolysis is the process by which fibrin, the principal proteinaceous component of blood clots, is enzymatically degraded. A key event in this process is the formation of the tissue plasminogen activator (tPA)–plasminogen complex on partially degraded fibrin, which leads to the conversion of plasminogen to plasmin, which then proteolytically digests fibrin. This system is tightly regulated by several inhibitors and by the clot architecture. Many components of the fibrinolytic system have roles beyond fibrinolysis (e.g. in ageing, basal metabolism, inflammation and cancer), but these will not be addressed in detail in this brief narrative.