Microwave-induced thermal acoustic imaging (MITAI) is a promising early breast cancer detection technique, in which image construction is based on thermo acoustics signals generated by the illumination of microwave pulses in tissue. In this work we have performed a microwave induced thermal acoustic signal generation simulation study using Comsol Multiphysics. A biological tissue model irradiated with pulsed microwave source from a waveguide is simulated and studied. We have evaluated the deposition of heat in the biological tissue irradiated by electromagnetic fields and the corresponding pressure variation in tissue due to temperature variations. It is then studied for different power levels to find out the minimum power required to generate the thermo-acoustic signal using 2.45 GHz microwave source. © 2006-2015 Asian Research Publishing Network (ARPN).