Syncope is more common in children with idiopathic pulmonary arterial hypertension (PAH) than in adults with PAH. Although syncope is associated with a poor prognosis in adult PAH, the clinical effects of syncopal events on disease severity and outcome in children have not been carefully investigated. This study assessed the prevalence of syncope in pediatric PAH and examined its clinical, hemodynamic, and prognostic importance. This retrospective study assessed clinical data, including syncope status, from 78 children (37 girls) with idiopathic and heritable PAH (median age at diagnosis, 11 years). Patients were classified as syncopal or non-syncopal, and clinical data from the two groups were compared. The primary outcome was a composite of lung transplantation and cardiac mortality. Overall, 31 (38%) children had a history of syncope at presentation. Median age at diagnosis, sex ratio, brain natriuretic peptide level, and 6-min walk distance at diagnosis did not differ between groups. The hemodynamic parameters of initial right heart catheterization were similar between the syncope and non-syncope group (mean pulmonary artery pressure, 67 versus 71 mm Hg; cardiac index, 2.9 versus 2.9 l/min/m², respectively). There was not significantly difference in event-free survival rate between two groups. Although syncopal events are common in children with PAH, our findings suggest that syncope may not be correlated with disease severity or outcome in pediatric PAH.