In the Preserje-Rakitna forest management unit, beech tree (n=661) quality was analyzed on permanent sample plots (n=194). Two methods of tree quality evaluation were used: 1) the standard method as used by the Slovenian Forest Service (SFS) during forest inventory, and 2) the supplemented method for evaluating timber assortment structure in the first and second quarters of tree trunks. Beech tree quality was relatively high; the share of peeled and sliced veneer was 18% of the total growing stock. The research hypothesis thatthe most significant indicator of the quantity of high-quality assortment is the tree diameter at breast height has been confirmed through the use of statistical modeling. In addition to the 15 tree, stand and site variables examined, the beech quality explanatory model also included the following stand and habitat characteristics: share of beech in stand basal area, total basal area, crown size, tree forking, social status, and development stage. Results have shown that the standard method of beech tree quality evaluation is inadequate. Flaws in the carrying out of field quality evaluation have been found. Improvements in quality evaluation and ideas for the transformation of the SFS quality grades into assortment volumes in the first and second quarters of beech tree trunks have been proposed.