We evaluated final adult height in 109 patients treated for childhood acute lymphoblasticleukemia on two multiarm Pediatric Oncology Group protocols between 1974 and 1981. Fifty-one patients received 2400 cGy cranial irradiation (XRT), and 58 patients received no XRT. All patients had no central nervous system involvement at diagnosis, achieved and maintained a complete response, entered puberty spontaneously, and had achieved final height. Height data were converted to standardized deviation scores. Mean age at diagnosis was 7.8±4.2 years. Distribution of heights at diagnosis was similar to that of the U.S. population. Relative to gender-specific heights for the population, female subjects in this study had lower attained heights than male subjects ( p=0.03). There was a monotonic trend of patients treated at an earlier age to have a reduction in final height ( p=0.057). Cranial irradiation was strongly associated with final height (mean standardized deviation score with XRT=−1.04 and without XRT=−0.14; p<0.001). Final height was not associated with age at diagnosis, prognostic risk group, or Pediatric Oncology Group protocol. By multivariate analysis, only XRT and XRT×age were significantly associated with final height ( p<0.001 and p=0.002, respectively). There was no significant gender effect. We conclude that XRT is significantly associated with reduced final adult height after treatment for childhood acute lymphoblastic leukemia. For survivors, therapy devoid of XRT does not appear to affect final height.