Adverse growing conditions for corn in Ontario during 1974, resulted in loss of crop yield. Field reports also suggest that the feeding value of this reduced yield may be affected. Corn samples from this crop were assayed for metabolizable energy (M.E.), net protein utilization (N.P.U.) and proximate analysis. Average M.E. value at 3219 kcal./kg. (85% dry matter) was some 3% less than expected standards. These samples ranged in crude protein from 7.6 to 10.9%, although protein quality in terms of N.P.U. was not affected.Differences in corn maturity at harvest are related to composition data; in particular sugar and starch levels. Samples of low M.E. value were considered ‘immature’ and contained lower proportions of starch and higher proportions of sugar than corresponding mature samples. M.E. values are correlated with crude protein, starch, sugar, pigment score and bushel weight. A correlation matrix involving M.E. and composition data is presented.Multiple linear regression equations show the expected changes in corn M.E. values with unit changes in various composition parameters.