Improving nitrogen (N) use efficiency requires consideration and integration of factors influencing crop N need with available management alternatives to improve the prediction of optimum N rates and avoid losses of N after application. The rate of N applied is often the most important factor affecting the efficiency of N use and the potential for N loss. Optimum N rates for corn production are frequently based on yield goals, but recent information suggests that soil characteristics and/or the results of N rate response experiments may provide more reliable estimates of crop N need. Once the required N rate is selected, additional management decisions can have important effects on N use efficiency, such as appropriate adjustments for non-fertilizer N contributions from organic N sources. These adjustments must recognize the important available N contributions from manures and previous legume crops as well as the substantial and often overlooked contributions from soil N. The results of diagnostic tests may provide additional information to guide the N rate decision, and the fertilizer materials used to apply N and the timing and placement of the N application can have important effects on N-use efficiency. In summary, N-use efficiency improvements rely on use of N rates appropriate for each production situation, and management of the applied N to minimize losses. Enhanced N use efficiency can increase economic returns to producers and lower the risk of negative environmental effects from N use.