Abstract: The effect of aqueous extract of leaf, stem and root of Imperata cylindrica and Chromolaena odorata at concentrations of 0, 5, 10 and 15% on germination and seedling growth of Centrosema pubescens were investigated. The experimental design used was completely randomized design with three replications. Results of the study showed that plant species, plant parts and their concentration had a significant effect (P < 0.05) on parameters measured. Aqueous extracts of both plants at all concentration levels inhibited germination percentage, germination rate, shoot and root growth of Centrosema pubescen and these effects were directly proportional to the concentration of extract. Chromolaena odorata extract was more inhibitory than Imperata cylindrica extract and the leaf extracts showed the most inhibitory effect.. Root growth of Centrosema pubescens was more sensitive to allelopathic effects of both test plants than on shoot growth. These results suggested that potential allelopathic substances produced by both plant species may hinder the success of introduction of C. pubescens into grassland invaded by the two weeds. Further studies need to be conducted to investigate their allelopathic behavior under field conditions against their associated species and mechanism of inhibition involved.