A model for the prediction of combustion and exhaust emissions of DI diesel engines has been formulated and developed. This model is a quasi-dimensional phenomenological one and is based on multi-zone combustion modelling concept. It takes into consideration, on a zonal basis, details of fuel spray formation, droplet evaporation, air-fuel mixing, spray wall interaction, swirl, heat transfer, self ignition and rate of reaction. The emission model uses the chemical equilibrium, as well as the kinetics of fuel, NO, CO and soot reactions in order to calculate the pollutant concentrations within each zone and the whole of cylinder.The accuracy of prediction versus experimental data and the capability of the model in predicting engine heat release, cylinder pressure and all the major exhaust emissions on both zonal and cumulative basis, is demonstrated. Detailed prediction results showing the sensitivity of the model to various engine design and operating parameters are presented and discussed.