Effects of man-made electromagnetic fields on living organisms potentially include transient and permanent changes in cell behaviour, physiology and morphology. At present these effects are poorly defined, yet their understanding may provide important insights. For the first time, we comparatively studied the effects of 18 Gigahertz and Terahertz radiation on pheochromocytoma PC 12 neuron-like cells, Bacillus subtilis and Giant Unilamellar Vesicles. Reversible membrane permeability was observed in PC 12 cells with no detrimental effects. The results provide new insights into radiation induced permeability effect in mammalian cells, suggesting a possible application of radiation for facilitation of efficient transport of biomolecules across cell membrane in drug delivery, where permanent permeabilisation or cell death is undesirable.