This study develops a model for a single cell electroporated by an external electric field and uses it to investigate the effects of shock strength and rest potential on the transmembrane potential Vm and pore density N around the cell. As compared to the induced potential predicted by resistive-capacitive theory, the model of electroporation predicts a smaller magnitude of Vm throughout the cell. Both Vm and N are symmetric about the equator with the same value at both poles of the cell. Larger shocks do not increase the maximum magnitude of Vm because more pores form to shunt the excess stimulus current across the membrane. In addition, the value of the rest potential does not affect Vm around the cell because the electroporation current is several orders of magnitude larger than the ionic current that supports the rest potential. Once the field is removed, the shock-induced Vm discharges within 2μs, but the pores persist in the membrane for several seconds. Complete resealing to preshock conditions requires approximately 20s. These results agree qualitatively and quantitatively with the experimental data reported by Kinosita and coworkers for unfertilized sea urchin eggs exposed to large electric fields.