Fifty percent of children with acute lymphocytic leukemia (ALL) may now be "cured". However, CNS impairments are occurring in these long-term survivors. It is not clear whether these problems are secondary to the disease, or to the mode of CNS trial prophylaxis. Cancer and Leukemia Group B (CALGB) in three separate clinical trials (CLB Protocols No. 7111, No. 7411 and No. 7611) has compared cranial irradiation (RT) with intrathecal (IT) methotrexate (MTX) to IT MTX alone. In an earlier study (CLB Protocol No. 6801) a comparison of IT MTX with no specific CNS prophylaxis was made. We have the unique capability of retrospectively evaluating the effect of CNS prophylaxis on large numbers of randomly treated patients. A pilot study to Protocol No. 761, conducted at Roswell Park Memorial Institue, also tested IT MTX. We will employ standardized neurological tests, standardized psychological and psychometric tests, CAT scans, EEG's and endocrine evaluation. There will be central review of these tests with evaluators blinded to the CNS treatment regimen received. This study will be a retrospective analysis where patients will be evaluated with the test battery on one occasion (Protocols No. 6801, No. 7111, No. 7411, No. 7611 and No. 7611 - pilot study). Approximately 150 disease-free children with ALL will be available for study for a two-year period. If both types of CNS prophylaxis are equally effective (i.e., cranial RT plus IT MTX versus intermediate dose MTX plus IT MTX), and one type results in a higher percentage of psychosocial and neurological sequelae, then this information is relevant to future trials and to recommendations for treatment in the community.