Sarcoidosis of bone has been observed in 29 patients for up to 43 years. It was present in the hands and/or feet in 26 patients, in the nasal bone in three and once each in the hard palate and temporal bones. There were three types of bone lesion: (a) lytic in 25 patients; rounded cortical or medullary lesions ranging in size from 1 mm to 1 cm in diameter, which on healing left a residual punched-out 'cyst'; (b) permeative in nine patients; these showed progressive cortical 'tunnelling' with remodelling of trabecular and cortical architecture; (c) destructive in three patients: rapidly progressive with pathological fractures and secondary joint surface involvement. Soft tissue swelling preceded the radiological abnormality for up to four yearts in 10 patients, accompanied it twice, followed it once and was absent on 16 (55 percent) occasions. Bone involvement was usually an incidental finding when sarcoidosis presented elsewhere. Other features included intrathoracic sarcoid (86 per cent), lupus pernio (48 per cent), skin plaques (41 per cent), ocular inflammation (48 per cent), nasal mucosal disease (24 per cent), lymphadenopathy (24 per cent), hepatomegaly (13 per cent), splenomegaly (10 per cent), and parotid enlargement (10 per cent). Pulmonary infiltration with or without lymphadenopathy was observed in three fifths and hilar adenopathy alone in one third of patients. Abnormalities in chest radiographs of patients with bone sarcoid resolved in only 20 per cent. Hypercalciuria was noted in one and hypercalcaemia in the other two patients with bone distruction.