Pulmonary arterial hypertension complicating congenital heart disease can progress to the life-threatening irreversible form known as Eisenmenger syndrome. When conservative treatments are inadequate, the risk of death as a result of the disease must be weighed against the risk associated with transplantation. Risk stratification has become a fundamental tool for the prediction of outcomes and the guidance of treatment in pulmonary arterial hypertension. However, the current risk scores for pulmonary arterial hypertension are not specific to pulmonary arterial hypertension with congenital heart disease, and the accurate prediction of risk of death in Eisenmenger syndrome is challenging. Here, experts in paediatric and adult congenital heart disease, Eisenmenger syndrome, risk stratification and pulmonary arterial hypertension have performed a comprehensive literature search to review current data on Eisenmenger syndrome risk stratification. Limited evidence was found. The only multivariable death risk-stratification model based on non-invasive predictors (age, shunt location, resting oxygen saturation, sinus rhythm and pericardial effusion) proposed thus far in Eisenmenger syndrome is awaiting external validation. Shunt location markedly influences outcomes and treatment strategies. Several risk factors have been identified as independent predictors in Eisenmenger syndrome, including the 6-minute walk distance, echocardiographic markers and serum brain natriuretic peptide. However, the use of these variables deserves further evaluation to improve risk stratification in patients with Eisenmenger syndrome.