The inheritance of crude protein (N .times. 6.25) in the intergeneric hybrids is of a complex type. Epistatic and dominant gene effects are most important and breeding programs should be based on periodic reciprocal selection. A breeding program based on additive gene effects could be applied in cases of sufficiently high h2 values. High protein and highly productive maize hybrids can be obtained by crossing selected lines and single maize hybrids with lines developed by using teosinte. Teosinte apparently is a promising and suitable donor or genes controlling high protein content in maize seeds.