This paper reports the results of a regression analysis of the relationship between planting date and corn yield. The study is based on experiments done at Agricultural Experiment Stations in Waseca, Lamberton and Morris, Minnesota. The experiments were conducted with several corn varieties. In addition to the date of planting, the estimated yield response equations include relative maturity as an explanatory variable. Other management practices included in the models are seeding and fertilization rates. Interactions among explanatory variables are estimated, also.