Pulmonary arterial hypertension associated with congenital heart disease is included in clinical group 1 pulmonary arterial hyperten sion. Eisenmenger’s syndrome develops over time as a result of large intra- and extra-cardiac arterial and venous blood communica tion. The pulmonary vascular resistance (PVR) increases and thus the systemic-to pulmonary blood flow reverses direction, producing a pulmonary-to-systemic shunt (Eisenmenger’s syndrome). Bosentan, an oral endothelin receptor antagonist A and B, is recommended in monotherapy and drug combination therapy in this group of patients. Liver toxic reactions occur in about 10% of treated patients but severe hepatotoxicity is rare. We present a clinical case of a patient with Eisenmenger’s syndrome due to large ventricular septal defect. The patient was for many years successfully treated with bosentan and subsequently developed drug-induced hepatitis.