Objective[|]Noninvasive methods for follow-up of pulmonary hypertensive children are limited. The main aim of this study was to determine the cutoff levels for uric acid and N-terminal pro-brain natriuretic peptide (NT-proBNP) for follow-up of Eisenmenger patients and their relationships with classical methods. To our best knowledge, this is the first study to investigate the levels of NT-proBNP and uric acid in pediatric Eisenmenger patients.[¤]Materials and Methods[|]Sixteen patients with Eisenmenger syndrome and 37 healthy children as controls were included in the study. The serum NT-proBNP and uric acid levels of the participants were measured. The echocardiography, six-minute walk test, and right cardiac catheterization data of the two groups were compared.[¤]Results[|]NT-proBNP>81.4 pg/mL and uric acid >3.5 mg/dL were found to be the most specific and sensitive points for predicting the severity of pulmonary hypertension in Eisenmenger syndrome. There was no significant difference between mean pulmonary arterial pressure and serum NT-proBNP level; however, the differences between pulmonary vascular resistance and serum NT-proBNP level and between mean pulmonary arterial pressure and serum NT-proBNP level were significant. There was no significant difference between NT-proBNP level and New York Heart Association functional classification or six-minute walk test distance. There was no significant difference between serum uric acid level and pulmonary vascular resistance, right atrial pressure, or mean pulmonary arterial pressure.[¤]Conclusion[|]It is too early to determine if serum biomarkers can replace classical diagnostic methods in Eisenmenger syndrome; further studies are required.[¤]