Antarctic coastal polynyas are areas of reduced sea ice cover within the ice pack and their associated surface waters are noted for sustaining enhanced levels of biological production during the spring and summer. Here we present satellite-based estimates of interannual changes in the areal extent, phytoplankton abundance, and primary productivity within 37 Antarctic coastal polynya systems over five annual cycles (1997 to 2002). The largest polynya studied was located in the Ross Sea (396,500 km2) while the smallest was located in the West Lazarev Sea (1040 km2). Most polynyas attained maximum areal extents in February of less than 20,000 km2. Mean polynya chlorophyll a from 1 September to 31 March ranged from 0.16 to 2.2 mg m-3, averaging 0.69 mg m-3. Daily production averaged 0.09 to 0.76 g C m-2 d-1. Mean annual primary production ranged from 18 to 161 g C m-2 yr-1, with most coastal polynyas exhibiting annual rates of production between 20 and 80 g C m-2. Total production (the product of the open water area and the spatial mean daily primary production rate) varied by 2 orders of magnitude, from 0.03 to 48 Tg C yr-1. Taken together, the Ross Sea, Ronne Ice Shelf, Prydz Bay, and Amundsen Sea polynyas are responsible for >75% of total polynya production. In eastern Antarctica, where 91% of all Ad¿lie penguin colonies are associated with a coastal polynya, the magnitude of annual production in polynyas explained 65% of the variance in penguin colony size.