Localized fibrous mesothelioma of the pleura is an uncommon neoplasm. Very rarely (there have been three previous cases) it may occur as an isolated mediastinal tumour. Such a tumour was present for at least 3 years in a 47 year old man, causing shortness of breath and superior vena cava syndrome. A mass weighing over 600 g was completely resected through a median sternotomy. The pertinent literature is reviewed.