In this paper, we describe the numerical modeling of magnetically induced heating of tissues in magnetic fluid deep hyperthermia. When placed in sinusoidal varying electromagnetic field, the Brownian particle rotation and Neel relaxation mechanisms induce in ferrofluid heat generation. In order to destroy tumors cells while preventing healthy tissues, such parameters as susceptibility of nanoparticles, exciting current parameters and intensity of magnetic fields should be calculated precisely. In this publication, coupled field problem resulting from Maxwell’s equation and Penne’s bioheat equation is discussed. Both sets of equations are solved using the finite element analysis method. We use a simplify model of human thorax with blood perfusion mechanism and tu-mor placed in it. Heat generation source in tumor is obtained by ferromagnetic nanoparticles. Magnetic and temperature field distribution is discussed in context of optimal tumor treatment.