The rapid expansion in the use of hybrid corn has been accompanied by a marked increase in the number of hybrids offered for sale to the Iowa farmer. These hybrids differ in their yielding ability, lodging resistance, maturity and other agronomic characteristics. Each year the purchaser of hybrid corn seed is confronted with the problem o f knowing which hybrid to buy. The Iowa Corn Yield Test attempts to help solve this problem by making available to the purchaser and producer of hybrid corn seed an impartial evaluation o f various hybrid combinations. It is believed that the results reported in this bulletin may be of value as an indication of the relative performance of various hybrids in different parts of the state. Records are published for yield, stand, moisture, lodging, ear height and dropped ears on each entry tested.