Exposure of cell lines and tissues to nanosecond pulsed electric fields has been associated to a number of biological relevant phenomena, suggesting the plasmatic membrane as one of the main interaction targets. In this context, a microdosimetric study able to predict trans-membrane potential and pore number distribution on the membrane seems to be particularly interesting. Thus to obtain these quantities, a quasi-static electromagnetic solution coupled with and asymptotic electroporation model is solved on a three-layered spherical cell. Consequently the role played by including or disregarding Debye description as well as by adopting different dielectric membrane models on such observables is discussed. © 2009 IEEE.