In this project, the interaction of cyclophosphamide (CYC) with DNA components is investigated using the density functional theory (DFT) at ωb97xd/6-31+G (d, p) level theory. The calculated results show that the amount of adsorption energy in the presence and absence of the electrical field is negative for all models and thermodynamically is exothermic, which is very favorable. The results of this study show the binding of CYC drugs to adenine and guanine is stronger than nucleobases.