A steady state analysis of H2SO4 sources and sinks in the Antarctic marine boundary layer was performed using measurements from project SCATE, Sulfur Chemistry in the Antarctic Troposphere Experiment. The calculations show that the SO2 levels needed to account for the observed gas phase H2SO4 ranged from about 17 to 300 parts per trillion by volume (pptv) with an average SO2 concentration of 100 pptv, far more than previous measurements of SO2 in this region which range between 7 and 17 pptv <Berresheim, 1987; Pszenny et al., 1989; P. Quinn, personal communication, 1996>. Boundary layer oxidation of DMS via an SO2 intermediate was found to be an insufficient source of H2SO4 in this region. Likely alternative sources of H2SO4 include oxidation of boundary layer DMDS and vertical entrainment of air from higher altitudes. ¿ 1998 American Geophysical Union