BACKGROUND The association of a univentricular heart defect with common arterial trunk is extremely rare. There is a lack of population-based outcome studies reported in the literature. METHODS The hospital records, echocardiographic and other imaging modality data, outpatients' records, operation notes, and other electronic data were reviewed. Patients were reviewed, and the final outcomes of surgery were observed. RESULTS Six cases (two males) with common arterial trunk presented over a 30-year period. Five had a complete unbalanced atrioventricular septal defect (83%) and one (17%) had tricuspid atresia associated with common arterial trunk. All had antenatal diagnosis. Two cases (33%) were excluded from initial surgical palliation due to Trisomy 21 in one and severe truncal valve regurgitation in one. Initial surgical palliation was performed in four cases (67%) at median age of 31 days (2-60) and consisted of disconnection and reconstruction of the pulmonary arteries and establishing controlled pulmonary blood flow. There were no early deaths. Conversion to cavopulmonary shunt was not possible in two due to severe airway problems in one and pulmonary arteries anatomy in one. They died at 11 and 16 months, respectively. Two patients (33%) underwent cavopulmonary shunt with 1 (17%) being alive at 18 months - 12 months after cavopulmonary shunt. The second patient proceeded to Fontan completion at 19 months but required catheter takedown 3 months later and died 3.5 years later. CONCLUSIONS Univentricular hearts with common arterial trunk carry extremely poor short- to medium-term outcomes. This should inform antenatal and postnatal counselling and decision-making.