The response of the Southern Hemisphere extratropical, atmospheric circulation to extremes of sea-ice concentration in summer is investigated using a fully-coupled climate model. Maximum and minimum sea-ice extremes were obtained from satellite-derived data and a twelve-month climatology for each case was created. Two ten-year simulations for each scenario were completed and the results compared. At the surface the sea-ice extremes directly affected the temperatures around Antarctica and through these the surface temperature and pressure gradients. The midlatitude surface westerlies are weaker in the maximum scenario while the polar easterlies expand further north. In the middle troposphere the zonal jet strengthens slightly and shifts equatorward in the maximum scenario. Comparisons of the sealevel pressure field and the 500mb geopotential height field for the two scenarios show that the leading mode of circulation variability, the Southern Hemisphere Annular Mode, tends toward negative polarity in the maximum sea-ice scenario.