A case is reported of gross lipomatosis of the heart which caused death by gross circulatory failure. The clinical, haemodynamic and angiographic diagnosis was Uhl's disease, and it was the post mortem examination which revealed the massive fatty infiltration of the heart; this involved mainly the right ventricle, but also affected the left ventricle to a major degree. Although fatty deposits in the heart have been recognised for some time, it is surprising to find that there have been extremely few publications on this subject during the last ten years; It is possible that a certain number of case reports of Uhl's disease in adults are really cases of lipomatosis of the heart which have not been recognised as such.