A method is provided for using magnetic nanoparticles to enhance microwave therapies for treating cells and tissues. The nanoparticles are designed to transduce microwave radiation into heat and furthermore, the nanoparticles may include specific tissue targeting and other functionality for enhancing in situ effects. In one embodiment, nanoparticles are introduced into a tissue system and a microwave field is applied. The nanoparticles react to the microwave energy by releasing heat thus heating the tissue and inducing hyperthermia (below 50°C) or thermotherapy (above 50°C). The nanoparticles can be designed for optimal heat production response at specific microwave frequencies and/or ranges of microwave frequencies where these frequencies may span the entire microwave spectrum, namely 300 MHz (3108 Hz) to 300 GHz (31011 Hz).