The first patient known to have died from asbestosis (1900) began work in 1885, approximately 5 years after the industrial use of asbestos began in Britain. Mineral particles were found in his lungs. No special comment was made of their fibrous nature then nor when the first case was reported in 1924. The various neoplasms attributed to asbestos in the next decades posed an additional question: What influence did the fibrous shape of the particles have on carcinogenic potential? The cogency of the problem was amplified by the identification in humans of asbestos-like neoplasms with a fiber other than asbestos (erionite) and by the production of such neoplasms in experimental animals with a variety of man-made inorganic fibers, often used as substitutes for asbestos. The lessons learned about asbestos may help guide us in evaluating current fiber problems.