Precipitation even samples from the Multi-State Atmospheric Power Production Pollution Study (MAP3S) precipitation chemistry network have been analyzed for both dissolved SO2 and sulfate. Because SO2 oxidizes rapidly to sulfate in collected samples, special sampling and handing techniques were used to preserve the dissolved SO2 for analysis. About 2 years of concentration data show the dissolved SO2 can contribute significantly to the wet deposition of sulfur in the eastern U.S. region during the cooler months (October--March). On an annual basis, this contribution is on the order of 5% of the total sulfur wet deposition. The SO2 component can be as much as 80% of the total sulfur in individual wintertime samples, and it can exceed 50% of the weighted monthly mean deposition at certain sites. These results are compatible with estimates made on the basis of known SO2 solubility properties. Regional measurements of nonurban SO2 air concentrations can be combined with precipitation pH data and the solubility of SO2 to make estimates of the likely contribution of SO2 to the total sulfur deposition over the eastern U.S. region. It appears, however, that these estimates should be calculated on an event-by-event basis, with a recognition of the many variables involved.