Acute lymphoid leukemia (ALL) is a malignant disorder characterized by uncontrolled clonal growth and proliferation of immature lymphoid cells of B or T lineage. These leukemic cells invade the bone marrow and spread to the peripheral blood, spleen, lymph nodes and other tissues and become clinically detectable. The origin of this disease is still unknown, however, it is associated with genetic and environmental factors such as exposure to ionizing radiation, chemical agents and alkylating agents. It is the most frequent malignant disease in childhood (80% of all leukemias in children) with an annual incidence of 2-3 cases per 100,000 children.hepatotoxicity is a frequent cause of treatment discontinuation in the maintenance phase of acute lymphoid leukemia. This discontinuation of treatment increases the possibility of hematologic relapse by up to 10%.