It is assumed that sarcoidosis is caused by inhalation of air borne agents in susceptible persons triggering the inflammatory reaction. The association of metallic dust exposure, such as beryllium and aluminium, and sarcoidlike pulmonary disorders is well known. The ability of man-made mineral fibres (MMMF) to cause granulomatous lung disease has not been appreciated until now. Recently, we observed the association of sarcoidlike granulomatous reaction and occupational history of glass fibre exposure. We hypothesized that there might be a relationship between MMMF exposure and the development of sarcoidlike granulomas. Therefore, the records of 50 sarcoidosis patients-who visited our outpatient clinic between 1996 and 1999 were reviewed. This revealed that 14 cases recalled a history of exposure to either glass fibres or rock wool, both MMMF fibres. The available obtained tissue specimens (n = 12) were reviewed. In six cases electron microscopy qualitative analysis of small fragments of the tissue revealed among others silica, aluminium and sometimes titanium. A distinct relation between fibre deposits fibre deposits and granulomas was found. These findings indicate that in susceptible people MMMF exposure might be related to a chronic granulomatous disease similar to chronic beryllium disease.