Two field experiments were carried out during 1990 and 1991 seasons at the Research and Experimental Center at Moshtohor to evaluate four new synthetic maize varieties (Moshtohor—1, 2, 3 and 4) as well as two local ones namely, Cairo—i and Giza-2 under three plant densities. The differences among varieties were significant for all of the studied characters. Moshtohor—4 produced the highest grain Yield per fad. and outyielded Cairo—i, Giza—2, Moshtohor—1, 2, 3by 17.81, 15.74, 6.92, 33.31 and 57.36%, respectively. While, Moshtohor-3 had the lowest values for yield and its components. All studied characters were significantly affected by plant densities. The highest grain yield/fad. was obtained when plants were spaced 25 cm apart in the ridge. Thè effect of the interaction between varieties and plant densities was significant for grain yield/fad. While, the remaining traits were not significantly affected. Moshtohor—4 and plants spaced 25 cm apart on ridge was about the optimal combination under the circumstances of this experiment.