Eleven cases of diffuse abdominal tumours in association with exposure to asbestos were discovered in the years 1958 to 1963. There were eight men and three women, all of whom had worked at the same factory. In seven of the men the age at death ranged from 38 to 78 years; one man is still alive at the age of 46. The women died at 44, 61, and 67. The survival time after the first exposure varied from 20 to 46 years. The shortest period of exposure was 10 months and the longest 32 years. All three of the main commercial types of asbestos had been involved in their working operations. Histological confirmation of the nature of the tumour has been obtained at necropsy in nine of the 10 deceased and at biopsy in six, including the survivor. A remarkable feature of these cases is the minimal fibrosis found in the lungs. In three men and one woman, asbestosis was not diagnosed during life, and no patient was completely disabled by pulmonary fibrosis.