An automated scanning electron microscope energy dispersive X- ray/image analysis system for characterizing particles extracted from human lungs was developed. Lung tissues from three cases of suspected occupationally induced lung disease were analyzed. The three cases included subjects who had been employed in heat treating and brazing of metals, tool and cutter grinding, and grinding of steel products composed of silicon-carbide (409212), aluminum (7429905), and cadmium (7440439). The tissues processed for particle analyses were taken from the paraffin embedded blocks used for light microscopic evaluation. Particles were isolated from the lung tissues by low temperature ashing and deposited on filters. Particles were automatically sized, analyzed for 32 elements, and classified according to their chemistry by the system. Particle compositions found for the three cases were similar. The major differences included the total absence of talc like particles in one case and reduced concentrations of aluminum, vanadium (7440622), chromium (7440473) and iron (7439896) particles, and an increased number of tin (7440315) containing particles in another case. One of the three cases conformed to the progressive interstitial lung disease associated with tungsten-carbide (11130737) workers. For each of the three lung specimens, large numbers of particles were associated with cemented tungsten-carbide products. The authors conclude that the automated analysis technique can quickly size, chemically analyze, and classify biological tissues according to their chemistry.