Parthenium hysterophorus L. is an aggressive weed of family Asteracea. It is native to the subtropics of North and South America but now has invaded Asia, Africa, and Australia, during the last 50 years. Since then the weed has not only naturalized itself in many countries but has spread at an alarming rate. In Pakistan it is spreading very fastly, affecting the Crops, Animal and Human Health related serious problems. Hence proper management of Parthenium is the cry of the day. Parthenium hysterophorus L. have allelopathic effect on weeds and crops of Pakistan and consider a serious threat to the Biodiversity of Pakistan and rest of the world. In Current published research works the Allelopathic effect of Parthenium hysterophorus L has findout on different Weeds and Crops of Khyber Pakhtunkhawa Pakistan through experiments. The results indicate clearly its potential regarding the stimulation and inhibition ability on tested crops and weeds species.