The influence of various drugs on the infectious aspect of hepatitis virus was studied in the present part. The pathological findings in the inoculated mouse were used as the criterion for the determination of the effect of drugs. Wintermin showed some raising effect on the sensitivty of the mouse against the hepatitis virus. ACTH-gel, ACTH, Pratonin A etc. sometimes showed some inhibitive action, though not a definite one, on the manifestation of the pathological changes by the virus. Because these drugs used for the present experiments were not the antiviral ones, no active inhibitive effect was observed, and further studies are needed on the effect of these drugs.