We present here a case study of cloud-mediated production of cloud condensation nuclei (CCN) recorded at Palmer Station (64¿46'S, 64¿05'W), Antarctica on 20 Jan 1994. Four instances of CCN bursts occurred on Jan 17, 19, 20 and Feb 7, 1994 when cloud base descended to the surface and dissipated under prevailing meteorological conditions. The most spectacular event occurred on Jan 20 when the CCN concentration was enhanced by a factor of four at 0.25% supersaturation (with respect to water) compared to the pre-event concentration. At 1.25% supersaturation, the corresponding enhancement was by a factor of seven. This indicated a larger production of aerosol particles in smaller size ranges. The elevated CCN concentrations were measured for over fifteen hours. The CCN activity spectrum during the event resembled the ones that are typical of previous measurements in the urban plumes of St. Louis and Denver. ¿ American Geophysical Union 1996