Line x tester technique was used in this study where ten new inbred lines were top crossed to two superior testers of maize. The obtained 20 top crosses and two checks (SC 128 and SC 2031) were assessed under 80 and 120 kg N/ feddan. In each experiment Randomized Complete Block design with three replications was used. Data recorded on days to 50% tasseling, ear height, ear length, ear dimeter, shelling % and grain yield ton fed-1. The cross M30 x M8 expressed the best mean value for days to 50% tasseling, while cross M34xM8 gave the best values for ear length and grain yield fed-1. Specific combining ability mean squares were more important than those of general combining ability for all traits revealing the important role on non-additive gene action in controlling these traits. The tester M8 was the best for earliness and grain yield fed-1. The best general combining effects were detected with line M25 for days to 50% tasseling and parent M 30 for grain yield plant-1. The cross M7xCIMMYT14 had the best SCA effects for grain yield. The cross M34xM8 expressed the best heterotic effects for grain yield fed-1 relative to both checks under all environments.