In 1994 the American Academy of Pediatrics recommended more liberal rules for the treatment of hyperbilirubinemia in healthy term newborns. Yet, the safety of moderate degrees of hyperbilirubinemia in healthy term newborns is debated. To evaluate the safety of moderate degrees of hyperbilirubinemia, we assessed neurologic condition of 20 healthy nonhemolytic term newborns with peak total serum bilirubin levels of 233-444 micromol/L and 20 control infants matched for sex and gestational age at birth. Neurologic condition was evaluated with techniques focusing on the presence of minor neurologic dysfunction: in the newborn period according to Prechtl, at 3 mo on the basis of the quality of general movements, and at 12 mo according to Touwen. Moderate hyperbilirubinemia turned out to be associated with a significant increase in minor neurologic dysfunction throughout the first year of life. At 12 mo a strong dose-response relationship between the degree of hyperbilirubinemia and the severity of minor neurologic dysfunction was present. Our results indicate that total serum bilirubin levels 335 micromol/L should be avoided.