Laboratory experiments were conducted to investigate the allelopathic suppression of aqueous extract and powder of Rumex dentatus L. leaves on seeds and pre-germinated seeds of Triticum aestivum L., Avena fatua L., R. dentatus L., Helianthus annuus L. and Zea mays L. on filter paper and soil by ‘Sandwich method’ and ‘Aqueous extract method’. It was observed that R. dentatus aqueous extract and leaf powder cause growth suppression in plumule and radicle of test species. Significant reduction of 44%, 44% and 82% were recorded in radicle length of wheat, maize and sunflower respectively in aqueous extract while powder extract suppressed growth of radicle by 54%, 65% and 40%. A remarkable decrease of 35%, 48% and 75% was recorded in plumule length of wheat, sunflower and maize respectively compared to their respective controls in petri dishes. A reduction in plumule length of 35% and 55% was observed in wheat and maize in Petri dish experiments. Same trend of growth reduction was found in soil experiments. Suppressive/inhibitory effects are assumed to be attributed to allelochemicals. It is suggested that R. dentatus aqueous extract can be used as weed management source.