To understand the influence of Chromolaena odorata on various agricultural crops number of studies have been assessed in this paper. Most of the researchers have found inhibitory effect of extracts of Chromolaena root, stem, leaf and inflorences on seed germination and seedling growth, root-shoot length and yield of various crops like maize, mustard, soyabean, mungbean, chickpea, Rice due to presence of more allelochemicals like alkaloids. Phenols, amino acids. Some researchers have found increase in crop yield like ragi, broccoli and okra due to presence of less allelochemicals.