Background: Pediatrics liver transplantations have been accepted as definitive treatment for end stage liver disease. Pleural effusion is the most common of pulmonary complications following liver transplantation in children. It can affect high morbidity including prolong oxygen dependence and hospitalization. Objectives: To identify the risk factors associated with posttransplant pleural effusion and patients' outcomes in Ramathibodi hospital in order to predict the prognosis after liver transplantations. Materials & Methods: This is a retrospective review of 140 patients who underwent pediatrics liver transplantations between March 2001 and June 2018 in Ramathibodi hospital. The medical records were missed in 31 patients, so 107 patients were included to this study. Then they were categorized into pleural effusion and no pleural effusion group. Pre and perioperative data including age, body weight at transplantation, etiology, pre-operative albumin level, lung disease, Pediatric End-Stage Liver Disease score (PELD)/Model For End-Stage Liver Disease score (MELD), intraoperative ascites, liver graft characteristics, length of stay in ICU/hospital and O2 dependence time were compared between 2 groups by multivariable logistic regression analysis. Results: Post-transplant pleural effusion occurred in 64 (59.8%) patients. PELD score ≥ 25, presence of intraoperative ascites, LDLT (left lateral segment donor grafts) were significant factors for postoperative pleural effusion. Prolonged length of stay in ICU (p = 0.013) / hospital (p = 0.018) and oxygen dependence time (p = 0.001) were significant outcomes in pleural effusion group following liver transplantations. Conclusions: Pleural effusion following Pediatrics liver transplantations incidence is high. Pre-operative risk factor assessment can use to predict the prognosis of post-transplant pleural effusion. Consequently, this may diminish morbidity and length of stay in hospital. [ABSTRACT FROM AUTHOR]