The use of light scattering from fibrous dusts has been investigated, and it was found that straight fibers have a sufficiently distinctive scattering pattern that may be counted electronically. Curved fibers may also be detected by focusing the light source so as to illuminate only a small, relatively straight section of the fiber. Theoretical and experimental data, and the design of a proposed instrument, are presented. The validity of the assumptions, which the proposed instrument contains, can best be probed by constructing a prototype based on the general outline given, and performing numerous measurements on the light scattering properties of individual fibers and field filter samples as a whole. The proposed instrument would fill a need in industrial hygiene to obtain rapid, accurate measurements of personal exposures to asbestos and other fibrous dusts.