In order to find antiviral compounds, alkyl group was introduced into the neurotropic structure of 1-phenyl-3-dimethylamino-1-propanol and activity of the resulting alkyl derivatives were examined against the Nakayama strain of Japanese B encephalitis virus and the PR-8 strain of influenza A virus. 1-(p-Decylphenyl)-3-dimethylamino-1-propanol and 1-(p-dodecylphenyl)-3-dimethylamino-1-propanol showed in vivo effect on the Nakayama strain, and 1-(p-ethylphenyl)-3-dimethylamino-1-propanol exerted in ovo activity on the PR-8 strain.