This report is a contribution of the Division of Plant Sciences, University of Missouri College of Agriculture, Food and Natural Resources. The work was supported by fees provided by companies submitting hybrids for evaluation. The University of Missouri's hybrid performance testing program began in the mid-1930s, with results first published in 1937. The number of entries in the program has grown from fewer than 50 in the early years to more than 215 today. The large number of commercial hybrids available makes selection of a superior hybrid difficult. To select intelligently, producers need a reliable, unbiased, up-to-date source of information that will permit valid comparisons among available hybrids. The objective of the University of Missouri's Performance testing program is to provide this information. The tests are conducted under the most uniform conditions possible. Small plots are used to reduce the chance of soil and climatic variations occurring between one hybrid plot and another. Results obtained should aid the individual grower in judging the relative merits of many of the commercial corn hybrids available in Missouri today.