An economic model of the demand for fertilizer is specified and equations for nitrogen, phosphorous and potash are estimated for individual states in the western United States. The results are acceptable from both an economic and statistical viewpoint. The estimated price elasticity of demand demonstrates considerable variation between states and nutrients. The quantity of each nutrient sold per acre has increased with expected crop price increases and land price increases. In general, the sales response to shifts in the crop production function has been very elastic. Future shifts in fertilizer demand will be heavily dependent on changes in agricultural productivity.