Apparatus for transcutaneous electrical nerve stimulation in humans, the apparatus comprising: a housing; stimulation means mounted within the housing for electrically stimulating nerves; an electrode array releasably mounted to the housing and connectable to the stimulation means, the electrode array comprising a plurality of electrodes for electrical stimulation of nerves; control means mounted to the housing and electrically connected to the stimulation means for controlling at least one characteristic of the stimulation means; monitoring means mounted to the housing and electrically connected to the stimulation means for monitoring at least one characteristic of the stimulation means; user interface means mounted to the housing and electrically connected to the control means for controlling the stimulation means; display means mounted to the housing and electrically connected to the control means and the monitoring means for displaying the status of the stimulations means; and a strap attached to the housing; wherein the strap is configured to hold the housing, stimulation means and electrode array at a specific anatomical location to treat pain.