Over the past two decades both the severity of Antarctic ozone depletion and the size of the Antarctic ozone hole have increased. A satellite-based, assimilated total column ozone data set and NCEP/NCAR meteorological fields from 1979 to 2000 have been used to examine the long-term evolution of the ozone hole and its dependence on the size of the dynamical vortex and the size of the region of low temperatures. Equivalent latitude zonal means of these data have been calculated to show more directly the expansion of the Antarctic ozone hole and its encroachment on the vortex edge. While the size of the dynamical vortex and the vortex region with temperatures below 195 K (where polar stratospheric clouds are expected to form) has changed little, the area with ozone below 220 DU (the contour defining the ozone hole) has steadily increased. Over the 20 year period, the severity of the ozone depletion within the core of the vortex has increased. This, combined with the nature of the mixing regimes within the polar vortex may explain the increase in the area of the ozone hole.