The author describes a flexible electrode which can be inserted percutaneously for a period of several days in candidates for an implantable electrical stimulating device for pain relief. This allows the patient a trial of stimulation which closely mimics that of the intended implantable system. If this trial does not give adequate pain relief in a variety of situations, the patient is not considered to be a suitable candidate for an implantable device. The trial of stimulation in no way obviates the need for careful scrutiny of the social and psychological factors accompanying chronic pain problems.