Pneumoconiosis was diagnosed by open lung biopsy in two dental technicians who had interstitial lung disease. Mineralogical analysis was performed to investigate the origin of the dust that had been inhaled. A marked accumulation of silicon and phosphorus was found in both cases. The hard metals chromium and cobalt were also found. Dental technician's pneumoconiosis is a complex pneumoconiosis in which such dust and hard metals may play a role.