One hundred eighty-seven patients diagnosed with acute lymphoblastic leukemia (ALL) between 1972 and 1975 were evaluated for height 6.4-8.8 years (median 7.2 years) from the time of diagnosis of their disease. All patients had been treated on protocols CCG-101/143 conducted by the Childrens Cancer Study Group. After induction of remission, patients received either cranial radiation plus six doses of intrathecal methotrexate, craniospinal radiation, or craniospinal radiation plus abdominal radiation, followed by systemic maintenance chemotherapy for either 3 or 5 years. No significant difference was observed in the distribution of height percentiles at the time of diagnosis compared to expected population standards. After treatment an excess (P less than 0.001) was observed in the proportion of patients in the lower percentiles in conjunction with a decrease in the proportion of patients in the higher percentiles. After adjustment for height at diagnosis, the only factor found to have significant impact on attained height percentile was exposure to craniospinal plus abdominal radiation (P less than 0.001) where there was a fivefold excess in the proportion of patients below the fifth percentile for height. Craniospinal radiation only was not associated with a greater reduction in attained height percentile when compared to cranial radiation only.