Recent estimates of particulate production from forest fires in the United States have ranged from 500,000 to 54,000,000 tons annually. This has been due partly to disparities in estimates of fuel that is consumed during the combustion process, but more to the choice of emission factors used to compute particulate production. This paper reviews the published data, and proposes new national estimates for wildfires and prescribed fires. The wide range of currently quoted emission factors, between 10 and 200 lb per ton for different fire behavior and fuel characteristics, is discussed. Grouped with the prescribed fire category are both low-intensity fires (used primarily in the south to reduce understory litter) and fires used for disposal of logging debris (slash fires). In addition, estimates summarizing particulate production on a seasonal-regional basis are also presented in order to underscore the need to recognize the cyclic and intermittent nature of the forest burning source.