In this study it is documented for the first time that the atmospheric ozone column density is decreased during solar proton events, GLEs (Ground Level Events), events with protons having energy exceeding 50 MeV and penetrating down to the ground. The ozone decrease was significant at the polar cap stations, Longyearbyen and Barentsburg at 78¿N, whereas it was not detectable at the auroral zone stations Murmansk (69¿N) and Troms¿ (70¿N). The duration of the depletion was limited to the days of the proton precipitation, and the depletion may be explained by the ability of energetic protons to produce nitric and hydrogen oxides in the stratosphere and their catalytic reactions with ozone. Similar events are identified in the Antarctic. ¿ American Geophysical Union 1992