Flow-limiting stenosis or total occlusion of coronary, cerebral, or peripheral arteries is very common. Minimally invasive treatment with balloon catheters optionally combined with stent implantation immediately relieves symptoms. However, renarrowing of dilated vessel segments due to excessive scar formation frequently reverses the initial success observed soon after treatment. Coating of balloons with antiproliferative drugs is a promising approach to overcome this problem. The coating of angioplasty balloon membranes is a challenging task. It must ensure homogeneous distribution of the antiproliferative agent and adherence to the balloon membrane during handling and on the way to the treatment site in a distant artery, where the agent should be immediately released and transferred to the vessel wall when the balloon is inflated. In vitro and in vivo testing methods are described. The impact of different kinds of balloons, drugs, additives, and coating methods has been investigated, and the results of representative examples including clinically tested products are presented and discussed.