A major challenge in the serologic diagnosis of infectious diseases in exotic birds is the limited availability of species-specific antibodies.The purpose of the current study was to determine if there is cross reactivity between commercially available anti-chicken IgY antibodies and immunoglobulins of several avian species, with particular emphasis on psittacines.To quantitate the reactivity with anti-chicken IgY, Western blot analysis was performed using plasma samples from many different avian species. Results were compared with gamma globulin fraction quantitation obtained by protein electrophoresis.By Western blot, 2 protein bands corresponding to the heavy and light chains of chicken IgY were identified in species from 21 avian orders using 1 of 2 rabbit anti-chicken IgY antibodies. Densitometric analysis showed that the amount of immunoglobulin estimated from Western blots correlated strongly with data from protein electrophoresis assays.The results demonstrate that some commercially available anti-chicken IgY antibodies exhibit good cross-reactivity with most avian species.