Thirty-seven vertical profiles of ozone and temperature were measured at McMurdo Station, Antarctica (78¿S) from 23 August to 31 October 1992. Total column ozone dropped from an initial 223 Dobson Units (DU) on 24 August to 158 DU on 27 September. The 12--20 km column reached a record low of 17 DU on 9 October, an 84% loss compared to the initial value of 106 DU. The most severely depleted layer was between 12 and 16 km which coincided with the volcanic aerosol layer (11--16 km) observed by aerosol counter flights and the Italian Lidar at McMurdo. By the end of September the polar vortex elongated and shifted away from McMurdo. Subsequent profiles, above 20 km altitude, were typically 15--20 ¿C warmer and ozone concentrations were 50--100% higher for the remainder of the measurement period. The 12--16 km layer, however, remained 80 to 97% depleted compared to the initial profile.