Preliminary pathological and mineralogical studies are reported on seventy-four sets of lungs from British coal miners who have been employed at the collieries included in the National Coal Boards's Pneumoconiosis Field Research. The degree of lung damage was considered in relation to the lung dust content and to the known dust exposures of the men concerned. Lungs were classified as having soft macules, fibrotic nodules or PMF. Those with soft macules had the lowest dust content but there was no significant difference between the dust contents of the lungs with fibrotic lesions and those with PMF. The percentage of non-coal minerals in the lung dust appeared to increase with the pathological classification from soft macules to PMF, and comparisons with the exposure data indicated a preferential retention of non-coal minerals, and especially of quartz, in the cases with the more severe lesions. Histological examination of the lesions showed the packing of dust was less close and the cellular response more vigorous with the lungs with the highest quartz content.