Secondary ion mass spectrometry (SIMS) was applied for the analysis of asbestos fibers. It was possible to identify the asbestos fibers by the pattern of the positive secondary ion mass spectrum. The image of the asbestos fibers was measurable by use of any major positive secondary ions. The smallest size of detectable asbestos fiber was about 5 and 1 μm in length and diameter, respectively. Using a fast atom bombardment (FAB) source instead of primary ion beam, asbestos fibers collected on a membrane filter were easily detected without any pretreatment. © 1991 Springer-Verlag.