Three-dimensional simulations of total ozone are reported for the 1996--97 Arctic winter. The record low ozone values observed by satellite in late March are well reproduced by the chemistry-transport model. The comparison between the chemically integrated ozone and a passive tracer with identical initialization allows us to discrimate chemical changes from variations due to dynamical processes. In addition to a substantial total ozone chemical loss (60 to 120 Dobson Units), the simulation reveals an dynamically-induced reduction of ~70 DU also responsible for the ozone minimum observed in the Arctic in late March 1997. ¿ 1998 American Geophysical Union