Ozone and temperature profiles were measured with balloon-borne instruments from McMurdo Station, Antarctica (77.85 ¿S, 166.67 ¿E) from late August to late October, on 38 occasions in 1996 and on 26 occasions in 1997. Minimum column ozone values of 147 DU and 141 DU were measured in 1996 and 1997, reduced from initial measurements in late August of 277 DU and 313 DU, respectively. These ozone minima are slightly higher than the lowest seasonal minimum detected in 1993, and are similar to observations of 1994, 1995. The observed recoveries during 1996, and especially 1997, as indicated by increasing temperatures and ozone above 20 km as the polar vortex became unstable, were among the weakest measured since 1986 with low ozone extending into late October. We continue to observe in both 1996 and 1997 almost complete ozone depletion over a layer more than 4 km thick and centered near 17 km, similar to the first such observation over McMurdo in 1995. The maximum observed thickness of this layer has remained relatively constant since 1995. ¿ 1999 American Geophysical Union