Gene therapy refers to modalities that transfer genes into target organs to restore activity of malfunctioning genes or to endow new functions that are presumed to remedy a variety of diseases. In the 1990s, there was a lot of hype regarding gene therapy as a panacea for diseases that had been regarded as incurable with traditional therapies. However, this early enthusiasm was quickly slowed down by fatalities in two cases of hurried gene therapy attempts in the US and France. The problem was primarily due to a lack of safe and efficient vehicles for gene delivery into target organs or cells. Over the last few decades however, significant progress has been made in the development of delivery vehicles. In late 2012, a gene therapy drug was approved for the first time in the Western world for a rare inherited disease, and more gene therapy drugs are expected to arrive on shelves in the near future.