Abstract: Both radiation therapy and chemotherapy are efficient methods of cancer treatment. Efficiency of the hadron therapy is based on the phenomenon of the Bragg peak. Parameters of the Bragg peak such as its distance from the entrance point and maximum magnitude depend on kind of particles in the therapeutic beam and its energy, physical properties of target’s substance and its chemical composition. During chemotherapy and some time after it chemical composition of tissues may be changed so it may leads to changes of the Bragg peak parameters in the case of combined treatment. In the article results of study of the influence of the chemotherapy on the dose-depth distribution are presented. The computational models are proposed and different schemes of chemotherapy are considered for the proton and carbon ion beams.