Background: Moringa stenopetala and related species are commonly used in folk medicine for various human diseases such as antimalarial, antihypertensive, antidiabetic and as antispasmodic. Objective: The aim of the study is to evaluate the effects of aqueous extract of M. stenopetala on blood parameters, and histopathology of liver and kidney in experimental mice. Methods: Fresh leaves of M. stenopetala were collected from Arbaminch area, Southwest Ethiopia, in November 2005. The leaves were dried and extracted with water. Three month-old Swiss albino male mice, which were kept under uniform laboratory conditions, were randomly divided into four groups (one group of controls and three experimental). (The control group was orally given 0.5 ml of distilled water, and groups II, III and IV were given the aqueous leaf extract of M. stenopetala using intragastric tube to achieve the required doses of 600, 750 and 900 mg/kg body weight, respectively once a day at 24 hours intervals for six weeks and then sacrificed). Blood sample was collected from each mouse and examined for hematological and biochemical parameters. Liver and kidney were removed, stained and examined for histopathological profiles. The effects of treatment with aqueous extract of M. stenopetala on hematological, biochemical and histopathology features were compared with control group following standard procedures. Results: Mice treated with 900 mg/kg of the extract per kg of body weight showed a significant increase in body weight compared to the controls (P=0.014). Neither a significant change in the weight nor in histopathology of liver and kidney were observed in the animals treated with aqueous extract of M. stenopetala compared to those of the controls. Serum glucose level (P=0.034) and serum cholesterol level (P=0.016) decreased significantly after six weeks treatment. Conclusion: The aqueous leaf extract of M. stenopetala is shown to increase body weight and reduce serum glucose and cholesterol level in mice. This indicates nutritional and medicinal values, but we cannot yet recommend its therapeutic use before more and complete studies are done.