Gene therapy is emerging as a potential strategy for the treatment of cardiovascular diseases such as restenosis after angioplasty, vascular bypass graft occlusion, transplant coronary vasculopathy, and homozygous familial hypercholesterolemia, for which no known effective therapy exists. Gene therapy requires efficient in vivo gene transfer technology. During the past decade, many gene transfer methods including viral transfer techniques were developed, and some are being applied clinically for human gene therapy studies. This paper reviews: (i) the major gene transfer methods; (ii) the cardiovascular diseases that may be targets for gene therapy; and (iii) the current status of clinical trials...