Rectal temperature of 126 term infants was measured on admission to the nursery following variable periods of stay with the mother in the delivery room. Fifty-nine infants who wore woolen hats after delivery had higher rectal temperature than 67 infants whose head was covered by loosely applied cotton diapers (36.5+/-0.5 degrees C vs. 36.3+/-0.5 degrees C, respectively; p=0.03). Among them there were fewer infants who were admitted with rectal temperature 36 degrees C (12 vs. 26, respectively; p=0.03). In multiple regression analyses accounting for head covering with woolen hats, birth weight, gender, delivery room temperature and length of stay with the mother, only birth weight and head covering with woolen hats were significantly associated with rectal temperature at arrival in the nursery (p=0.002 and 0.03, respectively), and only head covering with cotton diapers was significantly associated with rectal temperature 36 degrees C (p=0.03). Our data imply that covering heads of term newborns with simple woolen hats may reduce or prevent heat loss following delivery, and that adequate warming of infants is achieved during prolonged stay with the mother.