Coronary cameral fistulae in 208 orthotopic heart transplants performed at Papworth Hospital were examined. Sixteen fistulae in 208 heart transplants were identified (7.7%). This compares with a reported incidence of 0.2% or less in native hearts. Seven (3.4%) were similar to previously described fistulae to the right ventricle and were secondary to endomyocardial biopsy. Four (1.9%) arose from right or left coronary artery atrial branches and drained into the right atrium. We have called these 'suture line fistulae'. Five (2.4%) arose from left coronary branches at the apex; four of these drained into the left ventricle and one into the right ventricle. We believe these to be secondary to cutting needle biopsy of the apex of the donor heart before transplant and have designated them 'harvest biopsy fistulae'. One patient with a large fistula angiographically had no oximetric evidence of shunt at cardiac catheterization. Coronary cameral fistulae are an uncommon complication of heart transplantation and follow-up biopsy, and appear to be of no haemodynamic significance.