Thorium was determined in a liver autopsy sample from a person treated with Thorotrast ca. 40 y earlier. The decay products 228Ac. 224Ra, 212Pb, 212Bi, and 208TI from the 232 Th series were identified by direct y-spectrometry. Instrumental neutron activation analysis yielded a value of ca 22 g thorium per kg dry liver material. The total radiation dose to the whole liver was estimated in the order of 16 Gy.