The extremely low-frequency magnetic fields (ELF-EMF) are generated by electrical devices and power systems (1 to 300 Hz). In recent decades, exposure to ELF-EMF has emerged potential concerns on public health. Here, we discuss recent progress in the understanding of ELF-EMF biology with a focus on mechanisms of ELF-EMF-mediated disease and summarize the results of more recent experimental and epidemiological studies of ELF-EMF exposure effects on cancer, neurological, cardiovascular, and reproductive disorders. Current views on genomic instability effects, as well as scientific evidence about ELF-EMF therapy, are put forth. According to our literature review, exposure to ELF-EMF has an adverse biological effect depending on the current intensity, strength of the magnetic field, and duration of exposure. Accumulated epidemiologic evidence indicates a correlation between exposure to ELF-EMF and childhood cancer incidence, Alzheimer's disease (AD), and miscarriage. However, adult cancer does not show augmented risk caused by the ELF-EMF. Also, no consistent evidence exists in cardiovascular disease mortality due to ELF-EMF exposure. There is a lack of comprehensive mechanisms for explaining the biological effect of ELF-EMF. Eventually, more studies are needed to clarify the mechanisms of these magnetic fields.