Abstract: One hundred thirty four genotypes were evaluated applying simple lattice design during 2007 cropping season. In this study BHQ542 maize variety and other checks were used at two locations. The study objective was to determine performance of the test crosses, heterosis and heterotic patterns of the inbred lines and testers and to identify promising crosses for future advanced trial. All agronomic and physiological data were recorded and analyzed. There was significant differences among genotypes for most of the traits with few exceptions. Based on the mean value of grain yield, sixteen crosses at Awassa and only four crosses at Melkassa were superior to QPM hybrid (BHQ542) but no crosses out yielded this check in the combined data. However, five lines crossed with T1 and seven lines crossed with T2 gave superior yield than the second best common check BH540 in the combined data. In this study crosses with T2 were superior to that of crosses with T1. Heterosis value varied highly for most of the traits studied at individual location and across locations. The highest heterosis over mid and better parent for grain yield was 189.47% (L36xT2) and 100.8% (L36xT2) at Awassa and 172.22% (L18xT2) and 62.65% (L35xT2) at Melkassa, respectively. Among the twenty maximum heterosis of grain yield only L5, L10, L15, L16, L18, L23, L28, L35, L36, L37 and L41 were common for both locations.