Plots planted to corn (Zea mays L. var. Mo. 880) were treated with 0, 2.5, 5 and 10 lb/A of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) or 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) plus 0, 100, or 200 lb/A of nitrogen fertilizer. Yields of corn forage harvested 5 weeks after planting were significantly reduced by herbicidal treatments. Reductions were more pronounced on corn treated with simazine than with atrazine. In a given year, yields of corn forage from each successive harvest were reduced less, percentagewise, than the previous ones. Yields of corn grain generally were unaffected by herbicidal treatments, except when 10 lb/A of simazine were applied. Herbicides caused an increase in percent nitrate in forage approximately 5 weeks after treatment. Percent of nitrogen in corn forage rose sharply, approximately 5 weeks after planting, due to herbicidal treatments, especially on plots not treated with nitrogen fertilizer.