The region of the Southern Ocean exhibiting interannual variability in monthly averaged sea ice distributions has been mapped and analyzed using data from the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR) and the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR). Over the 13-year record from the two instruments (1973--1976 and late 1978 through mid-1987), interannual variability is particularly high for the early summer month of December, when 10¿106 km2 of the ocean had ice-covered conditions in some years and ice-free conditions in other years. This area of December variability is almost three times the ocean area consistently having ice-covered conditions in the 13 ESMR/SMMR Decembers. In contrast, in mid-winter the area of consistent ice coverage far exceeds the area of variability, which, in spite of the much greater ice coverage overall, is not as large as the area of variability in December. The mid-winter variability is confined to (1) a ring of variable width around the edge of the ice pack and (2) the location of the 1974--1976 Weddell polynya. Separation of the results to the ESMR and SMMR time periods shows that ice in the West Indian Ocean and the Ross Sea tended to be more expansive in the earlier, ESMR years than in the later, SMMR years, but that ice in the Weddell Sea tended to be less expansive in the ESMR years. In the Bellingshausen and Amundsen Seas, the ESMR years tended to have less summer ice than the SMMR years but not less winter ice. The images and plots provide a succinct summary of the range of spatial distributions of Southern Ocean sea ice during the ESMR and SMMR time periods. They can hence be used as a convenient base for comparisons with future sea ice distributions in the effort to identify occurrences of climate change. ¿ American Geophysical Union 1992