There is a widespread public perception that exposure to "EMF" is linked to cancer. This concern stems largely from a few epidemiological studies that appear to show an association between cancer and residence near power lines. However, the epidemiological evidence for such a link falls far short of that needed to conclude that a causal relationship exists, and examination of the biophysics leads to the conclusion that biological effects are implausible at the field strengths encountered in environmental settings. In a case such as this, where the epidemiological evidence for a link between an agent and a disease is weak to nonexistent and the effect is biophysically and/or biochemically implausible, laboratory evidence becomes critical for risk evaluation. The mechanisms of carcinogenesis are sufficiently well established that laboratory studies can be used to assess whether an agent has carcinogenic potential. There are approximately 100 published reports that have looked for evidence that power-frequency fields have genotoxic or epigenetic activity. These studies have found no replicated evidence that power-frequency fields have the potential to either cause or contribute to cancer. Of the few studies that have shown some evidence for carcinogenic activity, most have used exposure conditions with little relevance to real world exposure, none have been replicated, and many have failed direct attempts at replication. In conjunction with the epidemiology and biophysics, this leads to the conclusion that a causal association between power-frequency fields and cancer is not only unproven, but rather unlikely.