We investigated the possibility of producing chicken alpha interferon (ChIFN-α) in transgenic plants.The cDNA encoding ChIFN-a was introduced into lettuce (Lactuca sativa L.) plants by using an agro-infiltration transient expression system.The ChIFN-α gene was correctly transcribed and translated in the lettuce plants according to RT-PCR and ELISA assays.Re-combinant protein exhibited antiviral activity in vitro by inhibition of vesicular stomatitis virus (VSV) replication on chicken embryonic fibroblast (CEF).The results demonstrate that biologically active avian cytokine with potential pharmaceutical ap-plications could be expressed in transgenic lettuce plants and that it is possible to generate interferon protein in forage plants for preventing infectious diseases of poultry.