Chemotherapy causes neutropenia and increase susceptibility to infections. Morbidity and mortality due to infections remain serious problem in children with cancer. Decreased serum levels of Mannose-binding lectin ( MBL) may represent a risk factor for infections in children with acute lymphoblastic leukemia receiving chemotherapy. The aim of this study was to determine whether low MBL levels is associated with increased risk of infections in Syrian children with acute lymphoblastic leukemia. The study has been done at Children University Hospital in Damascus between 2013-2014. This study included 37 children diagnosed with acute lymphoblastic leukemia (ALL) who were candidates for chemotherapy, and the infections were identified depending on patients files. The levels of Mannose-Binding Lectin (MBL) was determined by Enzyme Linked Immuno Sorbent Assay (ELISA). The result was that MBL serum levels are higher in patients who did not develop infections compared to patients who developed infections, and all patients with low MBL levels developed infections in contrast to patients with normal MBL serum levels.