Laboratory studies were conducted to see the allelopathic suppression of wheat and mustard by Rumex dentatus ssp. klotzschianus (Meissn) Rech. It was observed that aqueous extracts, rain leachates and litter from dried and fresh shoot and roots invariably inhibited the germination and seedling growth of both the crop species. Soil collected from beneath Rumex dentatus also proved harmful for the germination and seedling growth. It is suggested that Rumex dentatus ssp. klotzschianus exhibits allelopathy against wheat and mustard.