To investigate the effects of low frequency electromagnetic fields (EMF) on the proliferation of epidermal stem cells, human epidermal stem cells (hESC) were isolated, expanded ex vivo, and then exposed to a low frequency EMF. The test and control cells were placed under the same environment. The test cells were exposed for 30?min/day to a 5?mT low frequency EMF at 1, 10, and 50?Hz for 3, 5, or 7 days. The effects of low frequency EMF on cell proliferation, cell cycle, and cell-surface antigen phenotype were investigated. Low frequency EMF significantly enhanced the proliferation of hESC in the culture medium in a frequency-dependent manner, with the highest cell proliferation rate at 50?Hz (P?