A master's thesis in the College of Medicine, University of Basra, discussed the effect of folate status on the level of methotrexate in the blood serum and the response to it in children with acute leukemia by student Duha Imran. The discussion took place in Umm al-Banin Hall at the College of Medicine, Basra University, and the electronic platform zoom was used to contact the member of the discussion committee, Assistant Professor Dr. Haider Saadoun Qasim from the Faculty of Medicine, University of Maysan. The thesis aims to study the folate substance in the blood serum of children newly diagnosed with acute leukemia and to compare it with the levels of this substance in the blood serum of healthy children, and to study the relationship of methotrexate level in serum with the level of folate before and after treatment. It concluded that children newly diagnosed with acute leukemia had a lower level of folate in the blood serum at the time of diagnosis, compared with healthy children, and then it increased in all children after the end of treatment. The level of methotrexate after the second high dose was higher in normal folate children compared with low folate children. The letter recommended shedding more light on the levels of folate in children newly diagnosed with acute leukemia, and attention to making all analyses to assess the general health status of children and follow-up methotrexate levels during chemotherapy to obtain a better result and reduce the side effects of this drug.