The metabolic syndrome is a cluster of potent risk factors for cardiovascular diseases. To provide information on the late complications of chemotherapy for acute lymphoblastic leukemia (ALL), the authors prospectively studied the frequency of overweight, obesity, and metabolic syndrome in survivors of ALL in the initial years after the completion of therapy. Children and adolescents were classified as having the metabolic syndrome if they met three or more of the following criteria: hypertriglyceridemia, low levels of high-density lipoprotein (HDL), high fasting glucose, obesity, and hypertension. Obesity was defined on the basis of Body Mass Index (BMI) (kg/m2) standard deviation scores or z-scores. Cutoff points for triglycerides and HDL were taken from equivalent pediatric percentiles with the cutoff points proposed by the Adult Treatment Panel III (ATPIII). Hyperglycemia was defined using the ATPIII cutoff points. Elevated systolic or diastolic blood pressure was defined as a value greater than the 95th percentile for age, gender, and height. Fifty-two subjects (29 male and 23 female) with a median age of 15.2 years (range 6.1-22.6 years) were evaluated. Median interval since completion of therapy was 37 months (range 13-121 months). All of them had been treated according to the ALL-BFM 90 chemotherapy protocol and none had received cranial radiotherapy. Of the 52 subjects, 25 (48%) were overweight (BMI z-score >1.5) and 3 (5.76%) were obese (BMI z-score >2); among them, 1 was severely obese (BMI z-score >2.5). Three criteria for the metabolic syndrome (high triglyceride levels, glucose intolerance, and obesity) were fulfilled by three subjects (5.76%). Twenty-nine subjects (55.7%) had at least one risk factor for metabolic syndrome. Hyperglycemia and hypertension were infrequent. Prompt recognition of the risk factors for metabolic syndrome and intervention seem mandatory to ensure early prevention of cardiovascular disease in survivors of ALL.