Issues pertaining to modeling of the propagation of electromagnetic waves in a biological medium are considered, including the wave refraction at the biological medium-free space interface. The behavior of the complex dielectric permittivity as a function of the frequency is analytically described. Power losses related to the reflection of waves propagating through an interface between two dielectrics are evaluated with allowance for the dielectric losses in biological media. Based on the results of analysis of the propagation of electromagnetic waves in biological media, it is possible to formulate technical requirements for radiators implanted into a given medium.