The study investigated the effect of staple-based mungbean diets on the physical and biochemical characteristics of school children (5-12 years) in selected orphanage homes in Imo State. Experimental research design was employed. Five (5) government approved homes were purposively selected, and a total of 95 subjects randomly sampled to the experimental (50) and control (45) groups across the homes. Staple-based mungbean diets replaced one of the daily three square meals of subjects in the experimental groups for a period of six months. After intervention, Body Mass Index of male (16.7 Kg/m 2 to 16.4 Kg/m 2) and female (17.5 Kg/m 2 to 16.9 Kg/m 2) subjects in the experimental groups reduced while Body Mass Index of male (17.8 Kg/m 2 to 18.7Kg/m 2) and female (15.9Kg/m 2 to 16.8 Kg/m 2) subjects in the control groups slightly increased, though not significant (p<0.05). Generally, biochemical characteristics of subjects in the experimental and control groups improved after six months. Significant (p<0.05) improvement was observed in the hemoglobin (6.7%), serum iron (29.8%) and TIBC (4.3%) of subjects in the experimental group, while the improvement observed in the hemoglobin (2.8%), serum iron (10.9%), and TIBC (1.1%) levels of subjects in the control group were not significant. Serum zinc level of subjects in the experimental (43.2%) and control (12.9%) groups significantly improved and clinical signs (skin rashes) significantly reduced (100%). It could be concluded that staple-based mungbean diets probably improved the physical and biochemical characteristics of school children studied. Therefore, are recommended for the feeding of growing children especially the school aged (5-12 years).