The basic juridical problems of patents are explained in order to identify systematic restrictions of the legal protection and thus of patent indicators. The analysis focuses on patents for plants and animals as a central part of innovations in agro-related biotechnology. A statistical evaluation of biotechnology patents at the European Patent Office is presented. This indicates that the restrictions of the European system in biotechnology are not as pronounced as often assumed. Patents turn out to be a valuable output indicator for R&D in biotechnology.