The heavy use of nitrogen fertilizers is contributing to groundwater quality problems in Hungary. Comprehensive field monitoring and research efforts are currently being carried out to establish environmentally sound agricultural management practices. As part of these efforts a one-dimensional simulation model was developed to evaluate and predict water and nitrogen movement in and below the root zone. The model considers the processes of saturated-unsaturated flow, convective-dispersive solute transport, transpiration, evaporation, snowmelt, plant water and nitrogen uptake, the effect of water stress on water and nitrogen uptake, and several nitrogen transformations such as mineralization, immobilization, nitrification, and denitrification. The model is capable of simulating water and solute transport through the vadose zone over multi-year periods. Two crops (corn and wheat) are currently being considered in the model.