Novel defrosting methods, such as dielectric heating [microwave (MW) and radio frequency (RF)] have been developed and recently used in domestic and industrial applications due to their volumetric heating capability, which has outstanding properties for food-quality preservation. In spite of the extensive use of these methods, nonuniform temperature distributions are frequently reported during dielectric defrosting; this problem causes microbial proliferation, increased drip losses, and color changes. This chapter is a compilation of recently published data on MW and RF defrosting including the dielectric properties (DPs) of frozen foods and frozen-food models in the MW and RF bands, the recent mathematical models developed in this field, and the approaches to uniform heating. The data described herein are valuable as a tool for research on the heating patterns during defrosting of frozen foods assisted by dielectric heating. These data may be useful for the development of improved MW and RF defrosting systems.