This study describes and evaluates a simple method of neuroprotective hypothermia for infants with hypoxic-ischaemic encephalopathy (HIE). Five term infants with HIE were cooled by applying soft, cold gel bags to the head. A radiant warmer, set to 34 degrees C, servo-controlled the temperature measured at a probe between the infant's back and the mattress. The infants' heads were shielded from the warmer. After 72 h, the infants were re-warmed by 0.2 degrees C per hour, by adjusting the radiant warmer. A rectal temperature of 34 degrees C was attained in a median time of 45 min. Mean rectal temperatures during cooling were 33.9 +/- 0.3 degrees C. There was good correlation between insulated back temperatures and deep rectal temperatures (r = 0.76). There were no major or irreversible adverse events during cooling. This method of cooling achieved rectal temperatures within the target range of 33-34 degrees C and re-warming was effective.