This chapter overviews the commonest electrolyte disturbances resulting in seizures, those of sodium, glucose, calcium, and magnesium. It presents etiology, clinical features and treatment for hyponatremia, hypernatremia, hyperglycemia, hypercalcemia, hypomagnesemia, hypermagnesemia and hyperkalemia. The seizures in electrolyte disturbance are generally successfully resolved by reversing the disturbance and do not recur in the longer term unless permanent cerebral damage is caused. Treatment should generally focus on reversing the perturbation rather than using antiepileptic drugs, which anyway are often ineffective in the setting of electrolyte disturbance. The major symptoms of hyponatremia relate to central nervous system dysfunction, and are much more common in rapid falls in serum sodium or when the levels fall very low. The usual approach to hyponatremia is the replacement of water and sodium in hypovolemic hyponatremia with normal saline, fluid restriction and sometimes a diuretic in hypervolemic hyponatremia, and by the treatment of the cause in euvolemic hyponatremia.