Białowieża Forest (BF) is widely known for its outstanding natural values. The debate about the management/protection model, able to maintain all relevant values of BF on a sustainable basis, has a very long history. Currently, the main role in this debate is played by groups and organizations claiming that the major threat for the biological richness of BF is related to local forest management. In this paper, an attempt is made to verify this thesis. The extensive literature research reveals that vascular plants are one of the most threatened (and best documented) groups of organisms occurring in BF. It was found, for example, that in case of Serratulo−Pinetum (one of the most important woodland community type occurring in BF) the floristic diversity declines at the rate 0.6 species per year. However, similar situation concerns many other groups of species (e.g. lichens) as well. The recession of many species does not take place in the managed part of the BF only. This problem concerns also the areas which, since a long time already, have been subjected to the strict protection, like the ‘Strict Reserve' of the Białowieża National Park (comprising ca. 7% of the BF, under strict protection since ca. 100 years). Several factors and agents responsible for the general deterioration of natural values of BF were identified. Among other things, many authors underline the negative impacts of natural, successional processes taking part in areas which were ‘liberated' from the direct human impacts. Such processes are a direct cause of loss among many herbaceous species, particularly helio− and termophilous plants. Another important reasons for decreasing trends in many important elements of the local biodiversity are: strong reduction of open and semi−open areas (disappearance of the so called ‘cultural landscapes'), climate change, air pollution, deer overabundance, compositional impoverishment of many tree stands, invasive species of plants and animals. In conclusion, there are many factors responsible for decreasing diversity of BF and most of them have nothing to do with the local forest management. To preserve possibly high levels of the natural values of BF for future generations, a wise and complex conservation strategy is needed. As many other similar examples from different places over the world clearly show, the core element of such a strategy should be the principle of active management approach and not the out of action principle of ‘doing nothing'