A biogenic sulfur emission inventory for the eastern United States and immediately adjacent portions of Canada is used in the ASTRAP model to estimate biogenic contributions to wet and dry sulfur deposition and atmospheric sulfate concentration, under the conservative assumption that all biogenic sulfur is transformed to sulfate. Simulations for summer conditions, in which biogenic sulfur emissions are greatest, are compared with simulations of transport and deposition of anthropogenic emissions of sulfur. The biogenic contribution to sulfur deposition during summer is shown to have a relative maximum in the southeastern U.S., about 5 to 10% of the total deposition from combined anthropogenic and biogenic sources, with only a 1 to 2% biogenic contribution indicated in the northeastern U.S.