Heart-lung transplantation has become an established treatment for end stage respiratory failure secondary to cystic fibrosis. The success of this form of treatment, and the increasing survival of such patients, suggests there will be an increased need for transplantation over the next decade. We have used cystic fibrosis population predictions and all cause mortality data to estimate the number of cardio-pulmonary deaths, due to cystic fibrosis, over the next decade and to estimate the number of such patients who are likely to benefit from heart-lung transplantation. We estimate that there will be between 85 and 127 potential transplant recipients with cystic fibrosis each year over the next decade. During 1990, 1991 and 1992 there were less than 40 transplants each year in such patients. These data emphasize the need to expand transplantation services and to maintain the availability of donor organs.