An ischemic facial paralysis was induced by injecting a vasoconstrictor into the facial canal in dogs sensitized to horse serum. On histopathologic section the nerve changes were similar to the changes known to occur in patients with Bell's palsy. The paralysis of Bell's palsy may be the result of ischemia and compression of the facial nerve within the fallopian canal in individuals showing a response of hypersensitivity to an active pharmocological agent acting locally.