Clinical imaging modalities provide clinical data with a variety of resolutions, clinical implementation costs, and various levels of complexity when applied and interpreted. Imaging techniques that are aimed at molecular imaging require the utilization of ionizing radiation that can pose safety risks and questions related to their frequent use. Microwave sensing and imaging (MSI) is emerging as an alternative method based on nonionizing electromagnetic (EM) signals that lie over a wide frequency range. The main advantages of using EM signals is the low health risk, low cost of implementation, low operational cost, ease of use, and user friendliness. The development of such systems may revolutionise treatments and contribute to advanced safe and cost effective detection and/or treatments. MSI has been used for tumour detection (breast), blood clot/stroke detection, heart imaging, bone imaging, cancer detection, and localization of in-body radio frequency (RF) ablation sources. The introduction of tailor made agents to enhance microwave (MW) dielectric contrast may provide a very useful clinical tool. In MSI applications, nanomaterials that change the dielectric constant when concentrated in tumours could be an elegant solution for tumour detection. MW devices used for sensing can also induce focused and controlled elevation of temperature in tissues (hyperthermia, ablation). This dual operation of MW devices can be combined with smart temperature responsive drug delivery systems to provide integrated tumour therapy and targeted drug delivery systems. The aim of this chapter is to provide an overview of this emerging technique and its potential in diagnostics and therapy.