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Large-scale forest scenario models are intensively used to make projections of forest areas of up to hundreds of millions of hectares. Within Europe, such projections have been done for 11 countries at the individual national scale, most often to foresee the long-term implications of the ongoing forest management. However, the validity of the models has rarely been tested. The aim of this study was 1. to validate the European Forest Information SCENario model (EFISCEN) by running it on historic Finnish forest inventory data, 2. to improve the model based on the validation, and 3. to project the Finnish forest development till 2050 with the improved model under alternative scenarios. The results of the validation showed that EFISCEN is capable of making reliable large-scale projections of forest resources for periods up to 50–60 years. Based on the validation, the model was improved concerning simulation of age development, thinning regimes and regrowth after thinning. The projection of the Finnish forests till 2050 with the improved model presented a maximum sustainable felling level of around 70 million m3 per year. That provides an average growing stock of 106 m3 ha–1 in 2050 and a net annual increment of 3.6 m3 ha–1 y–1. If the current trend towards more nature oriented forest management continues and 1.39 million ha of forests have been set aside additionally for nature reserves by 2050, the felling level could meet a realistic demand of 57 million m3 per year in 2050. Under the latter regime the average growing stock will have grown to 160 m3 ha–1 in 2050.