The therapy of acute lymphoblastic leukemia (ALL) in adults has built on the remarkable success achieved in the treatment of this disease in children. However, older age and other adverse risk factors seen more commonly in adults than in children have lessened the success of the treatment of ALL in comparison with what has been achieved in children. The treatment of ALL depends on the use of intensive multi-agent chemotherapy given over 6 to 9 months in combination with central nervous system prophylactic therapy with cranial radiation and intrathecal chemotherapy followed by maintenance chemotherapy for 2 to 3 years. This therapy has allowed younger patients with newly diagnosed ALL to achieve complete remission in 80% to 90% of cases, but has still resulted in subsequent relapse in most patients. For high-risk patients with ALL, allogeneic blood and marrow transplant (BMT) from a related or unrelated donor can improve the outcome compared with chemotherapy. The role of autologous transplantation in ALL remains uncertain, as does the role of allogeneic transplant in standard-risk patients. This issue continues to be the subject of large, randomized trials. New agents and improvements in supportive care bring the hope that more patients with ALL will be cured in the future.