Current study aims to investigate into the allelopathic potential of the different parts (leaf, bark, stem, twig and root) of three oil-enrich plant species of Bangladesh viz., Jatropha curcus, Ricinus communis and Aphanamixis polystachya. The aqueous extract of those plant parts were diluted into four different concentrations viz., 1:5, 1:10, 1:15, 1:20 (w/v) and tested against the seedling growth of jute, rice, wheat, radish, tomato, mungbean and mustard under control laboratory condition. A control (distilled water without extract) was also maintained in every cases and the bioassay experiment was replicated thrice. The results of this research showed that the shoot and root growth inhibition of rice, wheat, jute, tomato, radish, mungbean and mustard by leaf, bark, stem, twig and root extracts of J. curcus, R. communis and A. polystachya varied significantly. Compare to the shoot growth, the root growth of the test species inhibited more except J. curcus. The leaf and root have higher allelopathic potential than any other parts of the studied plants. Finally, it can be concluded here that J. curcus plant extracts has higher allelopathic potential than other two plants R. communis and A. polystachya. Therefore, J. curcus can be used as a candidate plant for isolation and identification of allelopathic substances for the development of new natural herbicides.