Some atmospheric electrical parameters, i.e., electric field, conductivity, and small ion concentration, measured at Athens, Greece, after the Chernobyl reactor accident, are analyzed and compared with their normal value and with measurements of radionuclide concentration and exposure rate in the air near the ground. The effects of the radioactive plume on the above electrical parameters, especially the conductivity, are very pronounced. ¿ American Geophysical Union 1989