The current investigation aimed at evaluating the yielding performance for 20 faba bean genotypes using randomized complete block design (RCBD) and alpha lattice design. The field experiments were conducted using alpha lattice design with three replications at Giza Agricultural Research Station during the two growing seasons of 2015/2016 and 2016/2017. Four statistical criteria being Coefficient of Variation (CV), Relative Efficiency (RE), P-value and power function were used to investigate the validity and usefulness of alpha lattice design over RCBD in accounting for the spatial variability. Results showed that alpha lattice design was more precise and effective in reducing the experimental error compared to RCBD indicating its great ability to detect the significance of small differences among genotypes means. The superiority of alpha lattice design over RCBD was clear in both seasons because they recorded the lowest values of each of CV and P-value beside the highest values of RE and power function. There was inconsistency in the rank orders of the genotype means resulted from alpha lattice design compared to RCBD. This result might be expected due to the different mathematical background of the two designs in removing plot to plot heterogeneity. Considering RCBD and alpha lattice designs simultaneously, results showed that genotypes number 6, 8 and 10 produced the highest seed yields in the 1st growing season with no significant differences among them while in the 2nd season, genotypes number 5, 9, 10 and 16 had the maximum seed yield