Background: Adults with systemic right ventricle have a significant risk for long-term complications such as arrhythmias or heart failure. Methods: A nationwide retrospective study based on the German National Register for Congenital Heart Disease was performed. Patients with transposition of the great arteries after atrial switch operation or congenitally corrected TGA were included. Results: Two hundred and eight-five patients with transposition of the great arteries after atrial switch operation and 95 patients with congenitally corrected transposition of the great arteries were included (mean age 33 years). Systolic function of the systemic ventricle was moderately or severely reduced in 25.5 % after atrial switch operation and in 35.1% in patients with congenitally corrected transposition. Regurgitation of the systemic atrioventricular valve was present in 39.5% and 43.2% of the cases, respectively. A significant percentage of patients also had a history for supraventricular or ventricular arrhythmias. However, polypharmacy of cardiovascular drugs was rare (4.5%) and 38.5 % of the patients did not take any cardiovascular medication. The amount of cardiovascular drugs taken was associated with NYHA class as well as systemic right ventricular dysfunction. Patients with congenitally corrected transposition were more likely to receive pharmacological treatment than patients after atrial switch operation. Conclusion: A significant portion of patients with systemic right ventricle suffer from a relevant systemic ventricular dysfunction, systemic atrioventricular valve regurgitation, and arrhythmias. Despite this, medication for heart failure treatment is not universally used in this cohort. This emphasises the need for randomised trials in patient with systemic right ventricle.