Controlled- and slow-release nitrogen (N) fertilizers have been commonly used in high-value applications, such as horticultural production. A variety of technologies are available that can enhance N-use efficiency when conditions for N loss exist. The varying modes of action of these products will be reviewed. Many of the traditional controlled- or slow-release products have not been economical for use in major grain crops because of high cost and low crop prices. High N prices and interest in improved N-use efficiency have increased demand for 'enhanced-efficiency' fertilizer products. New products are becoming available that offer the grower alternatives to conventional 'best-management practices'. Polymer-coated fertilizers seem to show particular promise. Research shows that enhanced-efficiency fertilizers can improve crop output per unit of applied N and reduce N losses. Studies in corn, wheat, rice, and potatoes show increased yields, better N-use efficiency, and greater net return for growers. Results of these studies will be presented.