Determination of enzymatic activities of commercial enzyme preparations. For a few years the registration of all agents used for wine treatment, including enzyme preparations, has been obligatory in Austria. According to the national legislation of Austria all official products are listed in a register. At the moment (May 2009) 1370 wine treating agents are registered in total, 179 of which are enzymatic preparations. Within the framework of quality management, the specifications, required by national legislation and the International Organisation of Vine and Wine, are randomly controlled analytically. The objective of this investigation was to determine and compare the activity of polygalacturonase, pectinlyase, pectinmethylesterase, glucosidase and cinnamoylesterase of 56 registered enzyme preparations. Experiments were carried out by means of the official spectroscopic methods of the 0.1. V and with some alternative methods. Differences in activity of polygalacturonase, pectinlyase, pectinmethylesterase were found between the commercial enzyme preparations. Furthermore in some products the glycosidase, which is known for releasing aromatic compounds, was effective. The results lead to the interpretation that cinnamoylesterase is only slightly or not active at all In all the tested preparations.