The Hohenpeissenberg ozone data reveals a conspicuous ozone decrease during the winter of 1991/92. Compared with the long-term mean, a decrease of about 10% could be observed in total ozone. A decrease of about 25% in the lower stratosphere was also seen. The possible causes for this ozone reduction were examined. At first the existing ozone trend which is considered to be caused by CFCs was eliminated. Because of contemporary, frequent high-pressure situations over Europe, this dynamic influence was also estimated and eliminated. There still remains an ozone deficit, showing that there must be additional reasons. Here the aerosols from Pinatubo should be considered. ¿American Geophysical Union 1994