This master thesis investigates the scope of patent protection when the subject matter of the invention is a naturally occurring plant gene. The recent legal changes in this field in Europe, in particular the implementation of the EU Directive on Biotechnological Inventions (EC/98/44) has altered the body of legally binding sources relevant for this question. This thesis seeks to discuss from a practical-legal perspective which acts or which types of uses of a patented naturally occurring gene confers to the patentee. In other words, which types of research and development are under the exclusive right of the patentee? One major finding is that the scope of such a patent is not easily defined. There is a margin of interpretation where the courts will have to determine difficult infringement cases. Another observation is that the scope of the protection for a naturally occurring gene is wide, which might become an obstacle to maintaining a vital public domain for research and development on that particular gene.