Corn quality affects dry grind ethanol yields. Average loss in ethanol yield due to grain quality can range from 3 to 23%. Corn quality factors (kernel composition, test weight, endosperm hardness, planting location, crop year and mycotoxins) affected or controlled by genetics, environment and postharvest practices were evaluated for dry grind ethanol yield. Significant effects of kernel composition, endosperm hardness, crop year, planting location, harvest moisture content and drying air temperature were observed on ethanol yields. However, effect of alfatoxin B1 (mycotoxins) or Stenocarpella maydis (fungus) on ethanol yield was not significant.