The seasonality of moisture sources for precipitation in Antarctica is studied with a Lagrangian moisture source diagnostic. Moisture origin for precipitation in Antarctica has strongly asymmetric properties, which are related to the Antarctic topography, seasonal sea ice coverage, and the land/ocean contrasts in the mid-latitudes of the southern hemisphere. The highest altitudes of the East Antarctic ice shield, where major ice cores have been drilled, have mean source latitudes of 45-40 degrees S year-round. This finding contrasts to results from previous Lagrangian studies, which detected a more southerly moisture origin due to too short trajectories. Results from Lagrangian moisture source diagnostics are thus now consistent with findings from general circulation models with tagged tracers. The moisture source characteristics for several major Antarctic ice-core drilling sites are presented. Implications for the interpretation of stable isotope parameters as moisture source indicators are discussed.