The Iowa Corn Yield Test attempts to supply performance records to the buyer and producer of various hybrids offered for sale to the Iowa farmer. Iowa has become “hybrid corn conscious” since 1935 when 3.1 percent of the Iowa corn acreage was planted to hybrid seed. In 1941, 95 percent of the corn acreage was estimated to have been planted to hybrid seed. Each year the Iowa farmer is confronted with the problem of knowing which hybrid to buy. The Iowa Corn Yield Test may help in solving this problem by giving some indication of the performance of various hybrids in different parts of the state. Records are determined for acre yield, percent stand, lodging, moisture, dropped ears and damaged kernels. Significant differences in yield and in other characteristics between hybrids, providing they are equal in stand, grown under the same environmental conditions may be attributed to genetic differences.