Industrial use of radiofrequency and microwave energy sources (nonionizing, high-frequency electromagnetic radiation) is a growing and widespread phenomenon, with projected risks of exposure to more than 20 million workers in the United States. A description of the nature of this form of electromagnetic energy is given, with emphasis on the variability of energy absorption by humans. The current state of biological research is reviewed, and a summary of the known effects of radiofrequency and microwave radiation exposure on animals and humans provided. These known effects appear to be principally thermal, similar to conventional electrical burn injuries, but with some unique systemic expression. Derangements of cardiovascular, gastrointestinal, endocrine, hematological, ophthalmological, and behavioral functions are well described in animal experimentation. Two patients are presented--one a young woman exposed to a high-density radiofrequency field in an industrial setting, leading to necrosis of the entire hand and wrist as well as to a constellation of systemic effects, and one an older woman exposed to excessive microwave radiation from a malfunctioning microwave oven, leading to chronic hand pain and paresthesias resembling median nerve entrapment at the carpus. The prevalence of potential exposure in certain industries is noted and recommendations for follow-up care of workers exposed to this form of trauma are delineated.