Stress-whitening occurs in many crystalline polymers when they are subjected to cold-drawing at atmospheric pressure and at room temperature. The exact structure and morphology of stress-whitening are still in contention, although it is widely believed that stress-whitening is a combination of crazes and voids. The healing of stress-whitening at room temperture may be divided into two stages: transient, which is a short time-dependent and post-transient. The post-transient healing phenomenon involves a long time-dependent or time-independent healing. Stress-whitening in the post-transient stage reaches a steady or permanent state. Healing of stress-whitening in the post-transient stage would occur when acted upon by an external agency, such as stress and temperature, or a combination thereof. A methodology has been developed to heal the permanent stress-whitening at or below room temperature in HDPE and PP. The study involved the following procedure: tensile samples of HDPE and PP were cold-drawn in an Inston testing machine at atmospheric pressure and room temperature to develop stress-whitening; the stress-whitened samples were subsequently, after days of rest, pulled in hydrostatic pressure environment at room temperature; the stress-whitened section was partially or completely healed depending on the magnitude of the applied stress (or strain) and the intensity of hydrostatic pressure.