In Iowa, corn historically has been grown in row widths of 30 inches or wider. During the last decade, many Iowa producers developed a renewed interest in the productiveness of corn in narrower rows. Much of this renewed interest was a result of the observed yield benefits of planting soybeans in rows narrower then 30 inches. In addition, the advancements made in farm machinery today have established effective means by which farmers can plant and harvest these narrow rows. As a result, research is needed to evaluate the effect of row spacing and related planting decisions on the yield of modern, high-yielding corn hybrids. The designed purpose of this study was to test the responses of different hybrids (based on relative maturity) to narrow row spacings. This study was conducted over three years, 1997-1999. In addition to this site, this study has been conducted at five other university research farms.