Nutritional status is an important variable when planning the treatment of children with acute lymphoblastic leukemia (ALL). We determined the nutritional status of children from Northern Mexico diagnosed with ALL during a 5-year period at a public university hospital. One hundred and two children were included. Evaluation by a clinical nutritionist through a food frequency questionnaire and anthropometrical measurements was carried out. Dual energy X-ray absorptiometry (DEXA) for body composition analysis was performed. Based on their body mass index (BMI) percentile, children were classified in four groups as underweight, normal weight, at-risk for overweight and overweight. Fifty-four patients were boys (53%) and 48 (47%) girls. Median values were: age, 6.0 years; weight, 23 kg, height, 118 cm. BMI median value was 16.7. In 78 patients studied by DEXA, median body mass was 24,335 g, with 66.4% from lean tissue, 23.5% from fat. Bone mineral content was 10.6%. Bone density was 0.754 g/cm2. The majority of children with ALL in Northern Mexico are well nourished at diagnosis and have a normal body composition. Early nutritional intervention is important to maintain this status and correct specific abnormalities. Pediatr Blood Cancer 2008;50:506–508. © 2007 Wiley-Liss, Inc.