Like electrical wires, neurons were recognized to convey information from one part of the body to another in the form of electricity. Due to its electrical nature, this transmission is very much dependent on the ions around their membranes. As in the case of all electrical messages of the nervous system, the action potential is a membrane potential change caused by the flow of ions through ionic channels in the membrane. With the help of the action potential simulation we test the effect of extracellular ion concentrations on the myelinated single nerve fiber action potential. Tests were designed to mimic the hypo/hyperkalemic and hypo/hypernatremic conditions. Our simulation results have shown that sodium ion channel conductivity is much more susceptible to the changes in the extracellular ion concentrations. Due to more susceptible nature of the sodium channel conductivity –with respect to potassium-, hypo/hyperkalemic conditions are much more dangerous for patients at least for neuronal conduction