Snow on Antarctic sea ice plays a complex and highly variable role in air-sea-ice interaction processes and the global climate system. This paper presents snow data collected during the past ten years, and reviews major findings. These include: differences in regional and seasonal snow properties and thicknesses; the unique consequences of snow on Antarctic pack ice relative to the Arctic (e.g. the importance of flooding and snow-ice formation); the potential impact if global change increases snowfall; lower observed values of snow thermal conductivity than those used in models; periodic large-scale melt in winter; and the contrast in summer melt in the Antarctic and Arctic. The new findings have significant implications for modelling and remote-sensing studies. Different snow properties from Arctic conditions are recommended for use in Antarctic models; similar differences could affect the interpretation of remote-sensing data over sea ice.