AbstractTwo groups of dogs were given dimethylnitrosamine (DMNA), a hepatotoxic drug, in a single lethal dose. Control dogs were allowed to die. Experimental dogs received life‐saving auxiliary liver transplants which were removed after recovery of the host liver or when rejection occurred. The histopathologic findings in the host livers of the two groups are presented. Remarkable variations were noted even among livers from the same group. Centrilobular and midzonal congestion and necrosis were the main findings but appeared less severe than one would expect in view of the lethality of DMNA in control dogs. In contrast to the changes noted with long‐term administration of the drug to dogs, there was nothing in this series to suggest cirrho