A 45-year-old male heart-lung transplant recipient reported reduced exercise tolerance two months post-transplant. Spirometry, right heart pressures, bronchoscopy, trans-bronchial and endomyocardial biopsy were normal. Investigations demonstrated posterior and leftwards herniation of the heart through the posterior pericardial window created during the transplant operation with secondary 90 degrees forward twist of the left lung. This phenomenon generated mild functional narrowing of the left pulmonary artery demonstrable on magnetic resonance imaging. Cardiac herniation with lung torsion is a rare finding post heart-lung transplantation and usually manifests in the early postoperative period with haemodynamic compromise, requiring immediate correction. Our case demonstrates that heart graft herniation and secondary partial lung torsion can occur in the chronic phase without catastrophic consequences.