The objectives of this study were 1) to compare final height and body mass index (BMI) between adult survivors of childhood brain cancer and age- and sex-matched population norms, 2) to quantify the effects of treatment- and cancer-related factors on the risk of final height below the 10th percentile (adult short stature) or having a BMI of 30 kg/m(2) or more (obesity). Treatment records were abstracted and surveys completed by 921 adults aged 20-45 yr who were treated for brain cancer as children and were participants in the multicenter Childhood Cancer Survivor Study. Nearly 40% of childhood brain cancer survivors were below the 10th percentile for height. The strongest risk factors for adult short stature were young age at diagnosis and radiation treatment involving the hypothalamic-pituitary axis (HPA). The multivariate odds ratio for adult short stature among those 4 yr of age or younger at diagnosis, relative to ages 10-20 yr, was 5.67 (95% confidence interval, 3.6-8.9). HPA radiation exposure increased the risk of adult short stature in a dose-response fashion (trend test, P < 0.0001). Adjuvant chemotherapy was not an independent risk factor for adult short stature. BMI distribution in survivors did not differ appreciably from that of population norms; however, in females, young age at diagnosis and HPA radiation dose (trend test, P < 0.001) were associated with risk of obesity. Except for patients treated with surgery only, survivors of childhood brain cancer are at very high risk for adult short stature, and this risk increases with radiation dose involving the HPA. We did not find a corresponding elevated risk for obesity.