In Part 2 the author discussed about the organic damages induced in the dog brains by the rapid administration of a large dose of Antabuse, and confirmed the deduction nade in Part 1. In the present experiment the normal dose, taking the usual dose administered to human as the standard, to dogs for a long period of time (0.01 g kg for 40 days) and studied pathohistologic findings in the brains of these animals. As the results the findings were similar to those reported in Part 2, namely, various pathologic changes could be found in the blood vessels of the cerebral cortex, gray matter, various subcortical nuclei and cerebellum, and also in places these pathologic changes extended to the cerebral parenchyma surrounding the blood vessels. The results in the present cases differed from those in Part 2 in that the changes in blood vessels were slighter in degree but more extensive and they were aged.