Selection of crop cultivars is one of the most important aspects of crop production. For any given crop, a farmer often grows more than one elite cultivar in a season to take advantage of genetic differences among cultivars for various traits such as stress tolerance and maturity. This is a sound management practice: farmers are using genetics to minimize the risks of crop production while maximizing the yield potential of their crop. Unfortunately this management decision often may be based on very limited genetic information leading to a faulty conclusion. Recent developments in DNA fmgerprinting techniques for cop species have provided the means to discriminate cultivars directly at the DNA level in a relatively comprehensive and precise manner. This workshop will review the basis of the most widely used technique, analysis of restriction fragment length polymorphisms (RFLPs), and its utility for cultivar discrimination and crop breeding with illustrations from corn breeding research.