Although the multi-agent chemotherapies in current use produce complete remission for a majority of patients with acute lymphoblastic leukemia (ALL), the prognosis for adult ALL remains discouraging due to a high incidence of relapse. Optimal post-remission therapy, therefore, has been a matter of vital concern. In some pediatric ALL studies, the use of high-dose methotrexate (MTX) as a consolidation therapy, has been shown to improve outcome, however, there has been no randomized controlled trials to test its clinical efficacy in adult ALL. With this concern, the Japan Adult Leukemia Study Group (JALSG) has planned a prospective randomized controlled trial comparing high-dose MTX and intermediate-dose MTX for ALL patients who are negative for BCR-ABL. Those who are positive for BCR-ABL can participate in a separate protocol.