Abstract: The aim of this research is to study the antibiotic activity of the plant Erythrina indica bark that makes this plant one of the medicinal plants which widely used in traditional medicine where is used to reduce the effect and complication of diabetes mellitus in many countries in the world. This study consist of two main steps, the first step is to induce diabetes in laboratory animals and he second step is to study the effect of the plant Erythrina indica bark extract on the laboratory animals.