Abstract Suberosis, a form of pneumoconiosis affecting cork workers, manifests itself as bronchial asthma or as a disorder of the peripheral gasexchanging tissues. X-ray of the lungs usually shows fine miliary mottling; and the microscopic appearances are those of extrinsic allergic alveolitis. The diagnosis is supported by the presence of serum-precipitins against mouldy cork dust. With correct diagnosis and avoidance of cork dust, the disease can be reversed.