Hyperglycemia in children with acute lymphoblastic leukemia (ALL) has been well documented in the literature. The purpose of the present study was to evaluate the clinical value of glycated hemoglobin (GHb) and fructosamine (Frc) in the long-term glycemic control of ALL patients. An attempt was made to identify the risk factors for hyperglycemia in ALL patients. The study group comprised 26 newly diagnosed ALL patients admitted to hospital during 1995-96. Patients with a history of blood transfusion or infection within the past 3 months were excluded from the study. White blood cell (WBC) counts, fasting blood glucose (FBG), GHb and Frc levels were analyzed in venous blood on screening day 0, before induction of chemotherapy. Frc analysis was repeated on the 21st day and GHb level on the 60th day of chemotherapy. FBG tests were performed before each dose of L-asparaginase, on days 21 and 60. None of the patients was obese. Although six children (23%) had hyperglycemia during the induction therapy, four of them had a GHb level higher than normal on admission. Only one patient who developed hyperglycemia had a family history of diabetes mellitus. Patients with a high initial WBC count (> 20 X 10(9)/L) had a significantly higher baseline GHb than patients with a WBC count below this level. GHb values returned to normal after achievement of complete remission. It is suggested that the leukemic process could impair glucose metabolism and baseline GHb may be used to monitor possible small changes in glucose homeostasis of ALL patients, prior to chemotherapy.