The objectives of this study were to determine the prevalence of hyperglycemia in extremely low birth-weight infants and to determine whether hyperglycemia increases the risk of early adverse outcomes (death or intraventricular hemorrhage of grade 3 or 4) and/or affects the length of hospital stay among survivors without intraventricular hemorrhage. The charts of all extremely low birth-weight infants (n = 93) admitted to Texas Children's Hospital (Houston, TX) during 2001 were reviewed. The highest daily blood glucose concentrations, highest dopamine infusion rates, highest daily percentage of inspired oxygen, and mean blood sodium concentrations were averaged over the first week of life or before death or occurrence of grade 3 or 4 intraventricular hemorrhage. Among survivors without severe intraventricular hemorrhage, the time ratio for blood glucose concentrations of >150 mg/dL was calculated. More than 50% of the infants had persistent blood glucose concentrations of >150 mg/dL during their first week of life. Early adverse outcomes were associated with the average highest daily blood glucose concentration through interaction with the Clinical Risk Index for Babies score and with the average highest daily percentage of inspired oxygen. The length of hospital stay was associated with the time ratio for blood glucose concentrations of >150 mg/dL through interaction with birth weight and the average highest daily percentage of inspired oxygen. These data confirm the high prevalence of hyperglycemia among parenterally fed, extremely low birth-weight infants and show that high blood glucose concentrations increase the risk of early death and grade 3 or 4 intraventricular hemorrhage and the length of hospital stay among survivors without intraventricular hemorrhage, which suggests that prevention and treatment of hyperglycemia may improve the outcomes of extremely low birth-weight infants.