Laboratory experiments were conducted to evaluate the allelopathic effects of different concentration
(5, 10, 20, 30, 40, 50%) of Calotropis procera(Aiton) W.T. leaf aqueous extractusing different indices for germination, seedling and physical growth of wheat (Triticum aestivum) and black mustard (Brassica nigra). Except for germination speed, results indicated that the extracts have such allelopathic potential which can significantly reduce the total germination percentage, germination Index, seedling vigorand certain growth parameters like shoot and root length and leaf area of the treated species. The rate of inhibition is concentration dependent. The present results mirror what happens under field conditions, where bare patches of neighboring plants with different sizes or poor regeneration around C. procearawas observed.