Hypothermia in infancy is not uncommon among the low socioeconomic population in various parts of the world. It is prevalent in Israel and is associated with severe morbidity and mortality. We tried to identify neonates at risk among the population of the Negev district of Israel. Ninety-one infant hospitalized with infantile hypothermia (IH) during the years 1974 to 1981 were identified. The neonates belonged to two distinct ethnic groups, Bedouins and Jews, and were compared with 120 healthy controls of similar background. Our data show that premature infants and babies with low birth weight born during the cold season to young (inexperienced) mothers of lower socioeconomic strata and who sustained perinatal morbidity are at risk for IH. It is suggested that parents of infants at risk should be approached while the baby is till in the nursery, be advised about the possibility of hypothermia, and institute the appropriate preventive measures.