Between 1970 and 1986, 120 children with central nervous system malignancy were treated with radiation therapy. These included 44 low-grade astrocytomas, 11 high grade astrocytomas, 32 medulloblastomas, 15 ependymomas/ependymoblastomas, 3 primitive neuroectodermal tumors and 8 pineal tumors. Seven children were treated without biopsy. Fifty-one treated children were evaluated for the effects of therapy on growth, endocrine function, IQ and hair regrowth. Mean height was 1.5 standard deviations below the mean height for the patient's age at study (range 0-5.7). Height was significantly less in patients receiving radiation to the pituitary and those with somatomedin-C deficiency. Height was also decreased with whole CNS radiation and spine dose > 20 Gy but not to a significant degree. Pituitary radiation in any dose increased the chance of endocrine deficiency (p = 0.004) and 21 of 51 patients had somatomedin-C deficiency. Mean IQ was 92.7 (+/- 18.8), with a slight trend toward decreased IQ with increasing whole brain dose of radiation. Hair regrowth was complete in 20 of 46 evaluated patients, diminished regrowth occurring with increasing volume and dose of radiation. No difference in the measured late effects could be detected with respect to age at treatment, sex, histology or location of tumor.