Rates for emission of NO and deposition of O3 were measured at a tropical forest site in Reserve Adolfo Ducke, near Manaus, Brazil. Two independent techniques were used to determine the NO flux: (1) a soil enclosure method and (2) a method based on simultaneous observations of NO and O3 vertical profiles at night, when NO is irreversibly removed by reaction with O3. Results obtained using the two techniques agreed well, giving an average NO flux of 5.2¿1.7¿1010 molecules cm-2 s-1 and an average vertical exchange coefficient of 2.2¿103 cm3 s-1. Sources of NO from tropical forest soils may be important for global atmospheric chemistry. Rapid removal of O3 was observed in the lowest levels of the forest. The nocturnal deposition rate was estimated to be 5.6¿2.5¿1011 molecules cm-2 s-1 through the 6 m level. The large deposition rate for O3 is consistent with the strong sink inferred from observations of ozone in the Amazon region. ¿ American Geophysical Union 1988