Abstract: Background and Objective: Enhancing yield of protein, oil and carbohydrate of maize grain (Zea mays L.) can be achieved either by increasing grain contents of these constituents or by increasing grain yield per land unit area. The main aim of the current investigation was to determine the effects of elevated plant density and genotype on corn grain protein, oil and carbohydrate contents and yields. Materials and Methods: A two year experiment was conducted in the field. The experimental design was a split plot with three replications. The main plots were devoted to 3 plant densities, i.e., Low Density (LD, 47,600 plants ha–1), Medium Density (MD, 71,400 plants ha–1) and High Density (HD, 95,200 plants ha–1) and sub plots to 17 genotypes. Results: The HD did not significantly affect grain protein, oil and starch contents but caused a significant increase of 27.57% for grain yield ha–1 (GYPH), 26.34% for protein yield ha–1 (PYPH), 27.57% for oil yield ha–1 (OYPH) and 28.15% for starch yield ha–1 (SYPH). The highest yields ha–1 of grain, protein, oil and starch were recorded under HD and the lowest under LD. The F1 cross (1×5) under HD gave the highest GYPH (14.94 t), PYPH (1.42 t), OYPH (0.582 t) and SYPH (10.67 t). Conclusion: The use of HD would overcome the negative impacts of interplant competition and lead to maximizing GYPH, PYPH, OYPH and SYPH, such maximization was more pronounced by the highest HD-tolerant genotypes.