1670 landraces from Tai Lake Region,which were taken out of approxi- mately ten thonsand of rice germplasm preserved at the institute,were evaluated for al- lelopathy.The results indicated that 35 entries had slightly inhibitory effects on seedling growth of Brassica campestris L.,68 accessions had inhibitory effects,49 rice varieties had fatal effects.Allelopathic potential did exist in rice germplasm,though the inhibitory ef- fects on aquatic weeds are needed to make further research.