Plants (crops and weeds) affect each other through allelochemicals, which may be released from living and dead organisms. Due to an increase in the number of herbicide ?resistant weeds and herbicides' negative effect on the environment, there is an effort being made to design alternative weed management strategies. Allelopathic studies offer a challenge a for a discovery of new compounds with new target side that may be able to control weeds. Crops producing allelochemicals can interfere with competing weeds sufficiently enough to allow significant reductions in the use of other weed management options, including synthetic herbicides. Some attempts enhancing the allelopathic potential of crops (rice, sorghum, barley and wheat) to control weeds are presented.