In a 65 years old male patient 38 cc of a 7.45% potassium chloride-solution was inadvertently infused within 3 hours into an epidural catheter on the first postoperative day. The epidural potassium chloride administration resulted in a paresis and painful paraesthesia of the patient's legs and a level of sensory blockade to TH 11. Furthermore vegetative symptoms like hypertension and tachycardia were observed. For therapy a single bolus of 40 mg dexamethasone was administered intravenously followed by an epidural infusion of sodium chloride 0.9% 99 cc/h for several hours. About 6 hours after the start of infusion all symptoms had disappeared. It is proposed that the use of colour-coded epidural catheter devices and coloured electrolyte solutions as well as infusion-pumps with a larger reservoir that reduce the frequency of syringe changes would be helpful in avoiding such complications.