The radiation in biological tissues is considered. It is studied how the kind of a biological tissue determined by its chemical composition and physical characteristics, as well as the beam parameters, affect the radiation depth-dose distribution. Numerical results are obtained using the application using the software package Geant4. The results of our simulations may be us ed for better understanding of processes that play a crucial role in hadron therapy. The efficiency of hadron therapy is based on the Bragg peak phenomenon and more precise localization of the biological effect of a therapeutic beam.