In this paper, the power density and specific absorption rat (SAR) distribution in multi-layered life tissues and exposed to electromagnetic field emitted from handheld cellular phone operating in the 900 MHz and 1800 MHz is studied. We modeled a life tissue by four layered system to represent skin-fat-muscles-organs respectively. Matlab program and finite difference time domain (FDTD) computations were used to evaluator the electric, magnetic field, power density and specific absorption rate. A one dimensional FDTD algorithm has been built, some simulations for electromagnetic wave through the life tissue is made. Results show that electro magnetic fields penetrate the life tissues and attenuate fast to reach zero at the organs layer. The absorbent power and SAR show maximum at the skin and fat layers