AbstractThe eukaryotic protozoan,Paramecium, was examined as a model for effects of pulsated electromagnetic fields (PEMF) on cells. A 72‐Hz PEMF similar to fields employed clinically increased cell division rates inParameciumby 8.5%. Two calcium transport mutants of these organisms showed differential responses to the same field. Verapamil, a calcium channel blocker, abolished any effect of PEMFs on cell division rates. A fluorescent probe that is thought to sense changes in membrane potential also manifested an altered response in the PEMF‐exposed cells whereas a fluorescent lipid bilayer fluidity probe produced evidence of decreased membrane fluidity in the exposed cells. An effect of PEMFs on ion transport mediated by either a direct or indirect effect on the cell membrane is suggestd by these stud