An experiment was performed to evaluate the phytotoxic effects of mesquite (Prosopis juliflora (Sw.) DC. by using its aqueous solutions. Extracts of all main parts of mesquite including leaf, stem and root were prepared in different concentrations to see their efficacy as phytotoxic components on wheat. The trial was conducted under laboratory conditions at the Department of Agronomy, Faculty of Agriculture, Gomal University, Dera Ismail Khan, Pakistan. Different concentrations (10, 20, 30 and 40%) were compared with control (tap water treatment). The use of aqueous extract in multiple concentrations showed significant effects over tap water treatment in almost all the parameters, however, germination and seedling vigour of wheat were gradually suppressed as the concentration of extract increased. It was concluded that 40% concentration of leaf aqueous solution was found most effective, which is evident that mesquite must be uprooted prior to the cultivation of any economically important crop.