A retrospective medical record review was completed for 264 consecutive newborns receiving phototherapy for hyperbilirubinemia to determine whether a "rebound" increase in total serum bilirubin (TSB) level occurs after termination of phototherapy. The difference between mean TSB levels at discontinuation of phototherapy and at rebound was calculated by paired t test. TSB levels at rebound were significantly lower than at discontinuation of phototherapy for infants weighing > 1800 g (positive and negative Coombs' test results). There were no statistically significant differences among infants in the smaller weight categories, regardless of Coombs' test results. Infants completing phototherapy for hyperbilirubinemia who are otherwise healthy do not require follow-up solely to identify a rebound bilirubin level.