A balloon sounding to 32 km altitude was conducted at the U. S. station on McMurdo Sound in Antarctica in October 1983. The purpose of the sounding was twofold. First, to determine the extent to which sulfuric acid aerosol from the April 1982 eruption of the Mexican volcano El Chichon had affected the Antarctic stratospheric aerosol layer and, second, to determine if sulfuric acid condensation nuclei are produced at high altitude in the Antarctic stratosphere as had been observed in the northern hemisphere during the late winter ‐ early spring period. The results indicate that stratospheric transport to the south polar region was very effective with aerosol mixing ratios observed to be similar to those in the northern hemisphere for the same time period. Observation of relatively high concentrations of condensation nuclei at high altitude and associated temperature variations tend to support the validity of an aerosol production process proposed to explain earlier northern hemisphere result