Study aim: Investigating the effect of adding oral L-carnitine to the treatment regimen of children with acute lymphoblastic leukemia in the maintenance phase on the level of liver enzymes. Design: A double-blind randomized clinical trial study using block randomization and stratified by age on 98 patients. Randomization will be done using the software of www.sealedenvelope.com website. Settings and conduct: The study will be conducted in the hematology and oncology ward of Ali Asghar Hospital in Tehran. The patients in the intervention and placebo groups will undergo the intervention for 2 months, and both groups will be examined every two weeks in terms of the mentioned liver enzymes until the end of the third month from the start of the intervention. Patients, clinical care providers and outcome assessors will be blinded in this study. Participants/Inclusion and exclusion criteria: Inclusion criteria: Children between 5 and 18 years old with acute lymphoblastic leukemia (ALL) undergoing chemotherapy in the maintenance phase, increased liver function test between grades 1-3, whose parents are satisfied with their child's participation in the study. Exclusion criteria: suffering from opportunistic viral and bacterial infections, suffering liver and kidney dysfunction, and other underlying diseases. Intervention groups: L-carnitine receiving group, placebo receiving group Main outcome variables: Serum level of liver enzymes including Alanine transaminase (ALT), Aspartate transferase (AST), Alkaline phosphatase, Bilirubin, and blood platelet count.