Avian metapneumovirus (AMPV) is the primary causative agent of severe rhinotracheitis in turkeys. It is associated with swollen head syndrome in chickens and is the source of significant economic losses to animal food production. In this study, we designed specific short interfering RNA (siRNA) targeting the AMPV nucleoprotein (N) and fusion (F) genes. Three days post-virus infection, virus titration, real time RT-PCR, and RT-PCR assays were performed to verify the effect of siRNA in AMPV replication. A marked decrease in virus titers from transfected CER cells treated with siRNA/N was observed. Also, the production of N, F, and G mRNAs in AMPV was decreased. Results indicate that N-specific siRNA can inhibit virus replication. In future studies, a combination of siRNAs targeting the RNA polymerase complex may be used as a tool to study AMPV replication and/or antiviral therapy. © 2006 Elsevier B.V. All rights reserved.