The aim of the study was to determine whether it in an industrial environment is possible to determine the amount of heartwood in Scots pine using UV fluorescence. The results show that it in many cases is possible to differentiate Scots pine heartwood and sapwood using the pinosylvin UV fluorescence. However, there is a large individual variation between different samples. Thus, it does not seem possible to develop a technology that, solely using UV fluorescence, is capable of industrially telling heartwood and sapwood apart for a sufficiently large amount of the Scots pine timber. The study has also shown that the difficulties in the industrial classification of heartwood and sapwood are not due to bad UV light intensity or crosscut surface roughness. Most likely the variations between the samples originate from the industrial drying process. A chemical analysis should be performed in order to find out whether the differences may be derived from strongly varying pinosylvin content of the wood.