In order to control the thermal environment inside the poultry building and minimize heat stress during the warmest seasons and hottest hours of the day, nearly the entire modern poultry industry around the world (both tropical and temperate climates) is using negative pressure tunnel ventilation with evaporative cooling system, provided by internal misting and/or a cellulosic cooling pad. Computational Fluid Dynamics (CFD) modeling has been used in some studies to evaluate the thermal environment in insulated poultry houses located in temperate climates (Blanes et al. 2008; Norton et al. 2007; Norton et al. 2009). However, there is no information on the use of CFD in uninsulated poultry housing such as those encountered in tropical climates like that of Brazil. The aim of this study was to develop and use a CFD model to analyze the distribution of the air temperature and velocity inside a typical uninsulated commercial Brazilian poultry housing equipped with negative pressure ventilation and an evaporative cooling pad system. The distribution of air velocity and temperature inside the facility showed good statistical correlation with the experimental data. Therefore the CFD model can be used to predict real time thermal environment behavior.