Various concentrations (5%, 10%, 15% and 20%) of aqueous extracts prepared from two weed species namely Chrozophora rottleri L. and Parthenium hysterophorus L and used for the present experiments to determine their allelopathic potential on growth and developmental changes on Rice (Oryza Sativa L.). The weed extracts showed an inhibitory effect on germination percentage, root and shoot growth, and fresh and dry weight of rice seedlings. The extracts of P.hysterophorus had more inhibitory effect at 20%concentration,than that of Parthenium hysterophorus L on growth parameters of rice.