Field measurements of hydrocarbon emissions from biomass burning in the cerrado (grasslands) and selva (tropical forest) regions of Brazil in 1979 and 1980 are characterized and quantified here. Regional consequences of burning activities include increased background mixing ratios of carbon monoxide and ozone, as well as reduced visibility, over extensive areas. Global extrapolation of the emission rate of hydrocarbons from these fires indicates that 6¿1013 g C of gas phase hydrocarbons and 8¿1014 g CO may be released annually from biomass burning. These emissions contribute significantly to the global budgets of hydrocarbons and carbon monoxide.