Providing adequate natural ventilation would reduce the building cooling load in tropical areas. This is regarded as a design moving towards 'green' or 'sustainable' building. Driving forces for natural ventilation in those hot and humid countries are basically wind-induced actions. This effect depends on the surrounding environment in a dense urban area, where buildings are closely built together. For a building located next to a vertical wall or a taller building, turbulent effects due to incident wind fields would be important. In this paper, the wind-induced indoor air flow in a building adjacent to a vertical wall is studied by Computational Fluid Dynamics under different ventilation conditions. Results are useful not only for providing better ventilation, but also for working out a fire-action plan in case of accidents. (C) 2003 Elsevier Ltd. All rights reserved.