© 2021, Turkish National Pediatric Society. All rights reserved.Background. Febrile neutropenia (FN) is a common and serious complication in patients with leukemia. Hemostasis and inflammation are two interrelated systems in response to infection. We aimed to investigate the course of thrombin formation in febrile neutropenia attack of children with acute lymphoblastic leukemia (ALL). Methods. Thrombin generation was monitored in children treated for ALL at diagnosis of febrile neutropenia (FN) (t0), at 48th hour of FN (t1) and after recovery from neutropenia (t2). Results. Twenty-nine patients and 50 healthy children as control were enrolled into the study. Mean endogenous thrombin potential (ETP) and mean peak value of thrombin results at t1 were significantly higher than at t0, t2 and control groups, respectively. A positive but statistically nonsignificant correlation between ETP values at t1 and duration of neutropenia was observed. Conclusion. Although thrombin generation is enhanced both due to chemotherapy or malignancy itself, our results revealed that thrombin formation also increased in neutropenic infection of children with leukemia.