Chinese hamster ovary (CHO) cells and human erythrocytes were pulsed by using square-wave electric-field pulses. This treatment induced their permeabilization. This phenomenon appears to be a three-step process of creation, expansion and annihilation of permeated structures. Altering the cell cytoskeleton, either with drugs, such as colchicine, known to depolymerise the microtubules in CHO cells, or by high temperature shock to affect the spectrin-actin network in erythrocytes, induced no modification on the first two steps of the electropermeabilization process, but was associated with a dramatic decrease in the stability of the electro-induced permeated structures. These experimental observations support the hypothesis of an implication of cytoskeleton in electropermeabilization in agreement with thermodynamic conclusions.