The potential of the GRACE mission for contributing to the assessment of Antarctic ice mass balance has been demonstrated in a number of previous studies. Here we present results from an analysis of the Release 04 monthly solutions by GFZ Potsdam. Using an adapted methodology we estimate ice mass changes both for the entire grounded ice sheet and for its large drainage basins. We detect ice mass loss which is dominated bychanges in the Amundsen Sea Sector and northwest Marie Byrd Land. Special emphasis is put on a thorough error assessment which exceeds previous work. Both the uncertainty due to the correction for glacial isostatic adjustment and the uncertainty due to GRACE product errors and the methods of their analysis are important. In this context, the need of combining GRACE with complementary observations and modeling is obvious. Weillustrate how this combination is being pursued within the German Research Foundation Priority Program (SPP 1257) project "The Antarctic ice sheet mass balance from satellite geodesy and modeling".