Occupational exposure to mineral dust causes pneumoconiosis and other diseases. A cytotoxicity assay to predict the potential of minerals to cause disease would be of great value as a prevention strategy. This study compares the ability of several minerals to generate the more potent oxidizing agent, hydroxyl radical (.OH), and their cytotoxicity and lipid peroxidation potentials. Crystalline silica, the most potent cytotoxic and pathogenic mineral studied, showed the least ability to generate .OH radicals while inducing the maximal lipid peroxidation. Coal mine dust, showing the maximal ability to generate .OH radicals, was the least cytotoxic in bioassays of toxicity and induction of lipid peroxidation. Based on these results, it would appear that the ability of minerals to induce lipid peroxidation provides a better correlation with known cytotoxicity and pathogenicity of minerals than does their ability to generate oxygen radicals.