To the pathologists who coined it, the term pneumoconiosis was useful to describe all pulmonary reactions due to the inhalation of dust. Under the impetus of compensation laws this group of conditions has received so much attention that today pneumoconiosis is almost a household word. But too few are aware of its original significance and even some medical writers use it interchangeably with the specific term silicosis. As a pathologist I prefer to retain the original meaning and use pneumoconiosis as a generic term to describe all forms of pulmonary reactions to inhaled dust, with no implication as to character, severity or effect on function. The two clinically important forms of pneumoconiosis that are known as silicosis and asbestosis are respectively due to inhaled free silica and asbestos dusts. Other forms have been given special names to indicate the kind of mineral that produces them, but such terms have little