An avian pox virus was isolated from cutaneous proliferative lesions removed from greater hill mynahs (Gracula religiosa) imported from Malaysia. Cutaneous inoculation of specific pathogen-free chickens and bobwhite quail with the mynah pox virus resulted in severe proliferative cutaneous lesions similar to those seen in the naturally infected mynah birds. Microscopically, the reaction in the chickens and quail at sites of virus inoculation was characterized by marked epithelial hyperplasia with ballooning degeneration and formation of cytoplasmic inclusion bodies. Inoculation of conjunctival and oral mucosae of chickens by applying pox virus with a cotton swab did not result in gross or microscopic lesions. In cross-protection studies, chickens and bobwhite quail immunized with either quail, fowl, pigeon, turkey, or psittacine pox vaccines were not protected from challenge with mynah pox virus. Following vaccination of quail and chickens with mynah pox virus vaccine, there was no resistance to challenge by quail, fowl, pigeon, turkey, or psittacine pox viruses. Significant protection against development of lesions following inoculation with mynah pox virus was attained only when the homologous virus was used as a vaccine.