Emissions of nitrous oxide by the soils of the Mata Atlantica subtropical forest were measured, on 21 days spread over one year, using a static chamber technique with natural flux calculation from nonlinear curves of chamber concentration versus time. The average of measured fluxes was 4.8 ng N cm-2 h-1 (n=131). Emission rates increased by an order of magnitude during and after rainfall, and a mean flux from this environment, weighted for mean weather conditions, was estimated as 3.6 ng N cm-2 h-1. These fluxes are comparable to others reported for humid tropical forests, among the highest for any environment. ¿ 2001 American Geophysical Union