This article reviews some important characteristics of microbubbles that give them therapeutic properties. It discusses the use of microbubbles and ultrasound for targeted delivery of adenovirus and nonviral vectors to myocytes and endothelial cells and for the dissolution of thrombus or potentiation of fibrinolytic agents for acutely thrombosed vessels. Potential applications, such as induction of angiogenesis, inhibition of neointimal hyperplasia, and in the setting of acute myocardial infarction and ischemic stroke,are discussed briefly.