Epithelioid granulomas, sarcoid type, are reported in four workers exposed to the inhalation of titanium dioxide dust. The granulomas were observed in the lungs, associated with respiratory insufficiency leading to death, in the hilum lymph nodes and liver. Diagnosis was done after a search of the occupational background of the patients followed by chemical and histochemical identification of the inhaled dusts within the lesions (morin and chromotropic acid methods and atomic absortion spectrophotometry) and experimental production of the disease in guinea-pigs. The harmful effects of titanium are not restricted to its dioxide, or to the inhalatory route. Different types of ceramic used in human implants and prostheses and the textile and aerospace industries use titanium.