The use of an electron microscope microprobe analyzer to identify submicroscopic particles of asbestos (1332214) was described. A transmission electron microscope was fitted with an X-ray energy dispersive microprobe analyzer. Single fibers of reference samples of crocidolite (12001284), amosite (12172735), anthophyllite (16829439), chrysotile-A, and chrysotile-B asbestos were dispersed in distilled water using an ultrasonic bath. They were then mounted on carbon coated gold electron microscope grids and analyzed with the electron microscope and microprobe. The analyses were performed with an accelerating voltage of 60 kiloVolts, as this had been found to give the best signal to noise ratio. The X-ray beam diameter was varied to cover the whole width of each fiber. X-ray counts for the various elements detected in the fibers were obtained by integrating their K-alpha X-ray peaks. After correcting for background absorption, the counts were used to determine the chemical composition of each fiber. The analytical results were presented in a table. They compared favorably with results obtained by bulk wet chemical analysis. For example, in the analysis of a single fiber of crocidolite, the chemical composition was found to be: silica (7631869), 53.7 percent; sodium-oxide (1313593), 4.6 percent; magnesium-oxide (1309484), 24 percent; calcium-oxide (1305788), 0.1 percent; manganese(II)-oxide (1344430), 0.1 percent; and iron(II)-oxide (1345251), 35.5 percent. Bulk wet chemical analysis gave: silica, 48.47 percent; sodium-oxide, 5.57 percent; magnesium-oxide, 2.72 percent; calcium-oxide, 0.92 percent; manganese(II)-oxide, 0.12 percent; and iron(II)-oxide, 35.83 percent.