The idea of carrying out a national forest inventory in Switzerland was first raised in the 1950s. It had become increasingly evident that such an inventory was lacking as a basis for evaluating the state of the forest in the whole country. But it was not until 1970 that this idea took concrete shape. And it took another ten years for the Swiss government to agree to the first inventory taking place. From the start, the National Forest Inventory (NFI) was a joint project of the Swiss federal administration and the Swiss Federal Research Institute WSL. It has now established itself as an objective source of information about the Swiss forest. On the national level, it is today the most important instrument for monitoring the sustainability of the management of Swiss forests, and it yields the main data needed for international reports on forests. The success of the NFI is at least partly due to the fact that it has met with widespread support from both the Swiss authorities and scientists. The NFI has, over the past 30 years, continuously developed both methodologically and in terms of content. Thus the first NFI's data catalogue was expanded to include, for example, numerous ecological parameters. Currently the fourth NFI is underway. It will mark the transition from a periodic to a continuous inventory. In the future, the survey results will be published roughly every three years. Reducing the intervals between inventories will, however, be associated with higher estimation errors. On the other hand, interesting new applications can be expected in remote sensing, as well as improved models of future forest development. Some new methods seem promising, like the so-called "small area estimation", which enables conclusions to be drawn about relatively small areas. However, if the NFI is to continue to perform its tasks adequately in future, it must receive sufficient funding.