Hepatic sinusoidal obstruction syndrome (SOS) is an illness with serious life effects that develops after hematopoietic stem cell transplantation (HSCT). We investigated the risk factors and clinical features of hepatic SOS in children following HSCT in 210 children who underwent allogeneic or autologous HSCT between 2009 and 2021 were analyzed in the context of SOS. The syndrome developed in 22 (10.4%) patients:frequently in neuroblastoma [24% (5/21)], hemophagocytic lymphohistiocytosis [57% (4/7)], and thalassemia major [22% (7/31)]. The median time from HSCT to diagnosis was 16 (6-38) days. Severe disease occurred in 8 (36%) patients, and mild/moderate in 14 (64%) and 4 patients died (18%). In univariate analyses, patient's age ≤ 2 years [odds ratio (OR)= 3.043, P = 0.028], pretransplant AST and ALT levels > 100 U/L (OR=3.576, P = 0.045), and chemotherapy/radiotherapy to abdomen before transplantation (OR = 3.162, P = 0.044) were determined as risk factors. In multivariate analysis, pre-transplant AST and ALT levels > 100 U/L (OR = 16.04, P = 0.010) and ferritin levels over 1000 mg/dl (OR=5.15, P = 0.047) were significant. The only independent risk factor on mortality was the age ≤ 2 years (P = 0.001). Although our study confirmed several risk factors for SOS, we failed to achieve some well-known risk factors. Precautions should be taken considering the factors affecting liver function before transplantation and the risk of SOS in infants receiving chemotherapy and radiotherapy before transplantation, such as neuroblastoma in which comparable results in respect to the chemotherapy only. The risk factors should be fully elucidated in multicenter studies to improve preventive and therapeutic strategies.