The bacterial origin of crown gall tumours, Agrobacterium tumefaciens was isolated 100 years ago. 70 years later, the findings that random integration of bacterial DNA into the host plant genome provided the potential of using Agrobacterium as a plant genetic engineering tool. Since the 1980s, Agrobacterium-mediated transformation on wide range of plants began developing rapidly. This review focused on the oncogenes of A. rhizogenes which is the causative agent of the hairy root disease and the application of A.rhizogenes in plant science.