Information on crop-water production functions when irrigating with saline waters is required to develop optimum irrigation strategies for various crops. A model was developed to compute these production functions by combining three relationships: yield and evapotranspiration, yield and average root-zone salinity, and average root-zone salinity and leaching fraction. The model allows plant-growth adjustment, and therefore evapotranspiration adjustment, to root-zone salinity. Using the model, product functions were computed for several crops. Calculated relative yields were compared with measured relative yields from experiments that had water quality and quantity as variables. Reasonable agreement between the two values provides some assurance of the model’s utility and reported production functions under field conditions.