The leading cause of death in the world is coronary heart diseases. According to World Health Organisation (WHO) cardiovascular disease caused over 18 million deaths in the world in 2005. Of these deaths, 8 million (44%) occurred in people under 60 years of age. In the recent years, of the several thrombolytic agents used clinically, streptokinase is prone of the most-often employed, particularly of its lower cost when coded to others. This book deals with streptokinase as a clinically important and cost-effective plasminogen activator. Streptokinase is a non-proteolytic extracellular protein produced by Streptococcus species. It is the best, least expensive, efficient, highly potent plasminogen activator of fibrinolysis and routinely applied in clinical medicine for thrombolytic therapy for the treatment of diverse circulatory disorders. Presently there is about 80- 90% of demand for streptokinase. As per market research 2011 report, Asia, Europe and North America are the leading countries worldwide in manufacturing and supplying streptokinase. This book provides more information about ? hemolytic Streptococci and the strain improvement methods to enhance streptokinase production.