A number of different laboratories reported on studies with orally administered interferons and cytokines. Their observations extend previous observations which showed that orally administered interferons and cytokines can exert both local and systemic effects. As difficult as it may be to understand how orally administered interferons and cytokines may exert both effects, the increasing number of laboratories that demonstrate biological effects with orally administered cytokines suggests that serious consideration be given to the possibility that orally administered interferons and cytokines can indeed exert effects. They also raise the possibility that these effects may have biological relevance for the treatment of human disease. Moreover, they may indicate that the nasal/oral region is a window on the environment. It is most important, however, to assure that these experiments are performed with special care to avoid presenting preliminary data that is not properly controlled. It is essential to carry out these studies with sufficient animals or patients to ascertain their significance; and to plan the studies as double-blind evaluations to avoid misinterpretations when subjective tests are used. Nevertheless, the overall data presented give one the impression of an area that should be pursued.