The Nitrogen Oxides (NOX) have been considered worldwide as one of the major causes of acid rain; one must also acknowledge both its phytotoxic effect and it role in the ozone formation process in the stratosphere. In that way, some countries are monitoring and restricting the emission of such pollutant gases within pre-established standards. Nevertheless, in Brazil, little has been done with relation to the NOX control and the Brazilian and International technical data on bagasse-fuelled boiler emission do not suffice. This work compare measured data on performance and emissions at the Monte Alegre sugarcane mill located in Minas Gerais, with predicted values from empirical correlations of NOX emissions. The influence of both boiler control, such as excess air ratio, and boiler load on emissions was also evaluated. (C) 2003 Elsevier Ltd. All rights reserved.