Phototherapy, an effective treatment for neonatal indirect hyperbilirubinemia, has guidelines for its initiation but none for its discontinuation. In our study, phototherapy was begun at a mean age of 90 hours in 28 full-term and 30 preterm infants with indirect nonhemolytic hyperbilirubinemia. After three days, phototherapy was halted at a mean bilirubin concentration of 13.0 +/- 0.7 mg/dL in term and 10.7 +/- 1.2 mg/dL in preterm infants, levels higher than those used by other investigators. Bilirubin rebound then occurred at a mean of 12.5 hours to a level of 0.86 +/- 1.0 mg/dL in term and at a mean of 14.1 hours to a level of 0.83 +/- 0.56 mg/dL in preterm infants. No complications were observed nor was there a need for reinstitution of phototherapy. Based on these data, discontinuation of phototherapy at higher bilirubin concentrations and earlier home discharge than previously described appear harmless for both term and preterm neonates.