A method for the determination of asbestos in airborne dusts is described, in which an X-ray diffraction technique is used with photographic recording. This paper describes the method as applied to amosite and chrysotile, but it is equally applicable to other types of asbestos. With a sample size of 30 mg the coefficient of variation is within 10 per cent. Over the range 15 to 100 per cent. of asbestos. Smaller sample sizes can be used if lower accuracy is acceptable.