This experiment was carried out during rainy season of 2003 and 2004 at Ibb experimental farm of the Research Station. Randomized complete block design (RCBD) was used with three replications. The experiment included 8 treatments of both crops combination ratios. Bean biological and grain yields increased as the proportion in spatial arrangement increased. For maize, the situation was the opposite. Yield components; harvest index, grain size and grain number/plant have increased in both crops. Considering equivalent maize and bean yield, total return, land equivalent ratio and relative crowded coefficient, it can be concluded that, best combination Ratios was 1:2 and 1:3. Based on aggressivity and competition index, results indicated that beans was positively dominated, and crops were not equally competitive, but widely differed in competitive abilities. Further trials are suggested to study optimal plant densities and efficiency of resources use.

Key Words :Equivalent maize (M) and bean (B) yield, land equivalent ratio, relative crowded coefficient, Aggressivity and competition index