Ultrasound irradiation of tissue and cells is effective in enhancing drug targeting, lowering systemic drug toxicity, and improving drug absorption rates. Ultrasound catheters to enhance the effects of thrombolytic agents have proven beneficial in treating patients with acute stroke, deep vein thrombosis, and pulmonary embolism in ongoing clinical trials. The revival of ultrasound for use in therapy after decades of dormancy has brought attention to usage in various fields such as thrombolysis, vascular therapy, cancer therapy, regenerative medicine, and gene therapy. Efficient delivery of a drug into target cells or tissues for therapeutic purposes has always been a big challenge requiring multidisciplinary efforts by experts in different scientific fields. Recent studies have shown that combining microbubbles and ultrasound energy could be applied to targeting or controlling drug release. In this paper, several therapeutic systems are cited as well as the mechanisms of ultrasound-mediated drug delivery. Current advances in molecular imaging and therapy will also be discussed.