A study of the mineral fiber content of the lungs of asbestos (1332214) textile workers was conducted. Specimens of lung parenchyma were obtained at autopsy from 98 persons who had been employed at a British textile factory and had died between 1964 and 1975. Twenty died from mesothelioma, 24 from asbestosis or lung cancer, and 54 from other causes. The specimens were digested with potassium-hydroxide. After digesting, ashing, and filtering they were analyzed for mineral fibers. Chrysotile (12001295), crocidolite (12001284), amosite (12172735), tremolite (14567738), anthophyllite (17068789), mullite (1302767), rutile (13463677), and iron (7439896) were detected at concentration ranges of 1.5 to 1389.6, 0 to 2056.9, 0 to 153.3, 0 to 203.7, 0 to 15.2, 0 to 246.8, arithmetic mean fiber mass concentrations of chrysotile, crocidolite, amosite, tremolite, and anthophyllite were 6.0, 8.4, 4.2, 8.5, and 0.2 micrograms per gram, respectively. Most chrysotile fibers had lengths and diameters of less than 5 and 0.25 microns, respectively. Most crocidolite and tremolite fibers had lengths greater than 5 microns and diameters greater than 0.25 microns. Higher average chrysotile and crocidolite concentrations were found in the lungs of subjects who died from asbestosis and lung cancer than those who died from mesothelioma or other causes. The chrysotile concentrations increased with increasing severity of fibrosis. The concentrations of amphibole asbestos forms were not related to fibrosis severity. The extent of fibrosis did not increase with years of exposure. The concentration of amphibole fibers tended to increase with years of exposure, whereas chrysotile concentrations remained relatively constant. The authors conclude that amphibole fibers may be selectively retained in the lungs.