Summary The increasing use of beryllium in a variety of industries continues to be a hazard. New cases are still being reported to the UK Beryllium Case Registry, now numbering 60 in the period 1945-1988. The majority of cases follow inhalation which results in acute beryllium disease (chemical pneumonitis) or more commonly chronic beryllium disease--a granulomatous pneumonitis. Granulomatous skin nodules also occur following local implantation. The clinical and radiological features are briefly described with the emphasis on pathology and immunology. Laser microprobe mass spectrometry analysis of tissue sections is a major advance in diagnosis. Detection of beryllium distinguishes the granulomas of chronic beryllium disease from other diseases, in particular sarcoidosis. The role of beryllium lymphocyte transformation tests is discussed. Chronic beryllium disease is steroid dependent and local excision of skin lesions appears to be curative. There is no evidence that beryllium is carcinogenic.