Over the last two decades, clinical trials using gene therapy medicinal products (GTMPs) have been carried out for a large number of rare, inherited monogeneic disorders as well as common multigeneic diseases such as cancer, cardiovascular and infectious diseases including AIDS. Despite some early difficulties and setbacks, the gene therapy field has slowly progressed and, nowadays, offers the promise of novel treatments for a growing number of diseases. On the other hand, gene therapy approaches are often associated with additional risks due to limited clinical experience with a given gene transfer system, long-lasting effects of the therapeutic gene, and/or a complex mode of action. As a result, specific regulations and guidelines have been introduced within the EU to help address these uncertainties. This article summarises the legislative framework and will provide an overview on the regulatory requirements for clinical trials and marketing authorisation applications.