The number of patent applications is an important indicator for the inventive activities of a country. R&D is considered to be the most important influence factor for inventions. In the nineties the number of patent applications has increased in Germany on the aggregate level in spite of a decrease in R&D expenditure. The aim of this project was to explain this paradox on the micro level, i.e. the level of the enterprise. For this reason the data of the Mannheim Innovation Panels have been merged with patent data from the European Patent Office and the German Patent Office using a self developed heuristic text search engine. Using econometric panel count data models we analysed the stability of the R&D-patent relationship over time. It was found that the propensity to patent has decreased over time, but the productivity of R&D has even more increased.