The embryonated hens egg can be infected with influenza A virus in laboratory experiments leading to death of chick embryos within 8 days post infection. This model can be used for rapid and reliable in vivo evaluation of potential anti-influenza inhibitors. It offers a realistic alternative to experiments with small laboratory rodents. By an example of treatment with the antiviral drugs amantadine (CAS 665-66-7), rimantadine (CAS 1501-84-4) and zanamivir (CAS 139110-80-8), it could be demonstrated that chick embryos survive a lethal influenza A virus infection when these drugs are administered immediately before or after the infective agent is inoculated. In conclusion, the use of influenza virus-infected chick embryos for evaluation of new antiviral substances can lead to a considerable reduction in the number of small laboratory rodents required.