Prescribed fires are likely to re-emit atmospherically deposited mercury (Hg), and comparison of Hg storage in areas affected by prescribed fire to that in similar unburned areas may provide cross-validating estimates of atmospheric Hg deposition. These fires are common in the southeastern United States (US), a region of relatively high Hg deposition compared to the rest of the US, and are thus a potentially significant source of re-emitted atmospheric Hg. Accordingly, soil Hg was determined in soil layers of a prescribed fire experiment in a Florida pine forest. The Hg deficit in the annually burned forest floor relative to the forest floor unburned for 46 years agreed to within 5% of an independent estimate of atmospheric Hg deposition to this site (0.171 g ha^-1 yr^-1). Consideration of other potential inputs and outputs of Hg suggested that atmospheric deposition was the primary input of Hg to the site. If extapolated, results suggest that prescribed fires in the southeastern US mainly re-emit atmospherically deposited Hg and that this re-emission is less than 1% of US anthropogenic emissions.