SUMMARYFord, J. 1974. Concepts of subspecies and hybrid zones, and their applications in Australian ornithology. Emu 74; 113–123.Taxonomic, evolutionary and biological concepts of the subspecies are discussed. Criticisms of taxonomic and evolutionary concepts are briefly reviewed. Some aspects of the subspecies in relation to the biological species concept and hybrid zones are discussed. Currently there are two schools of opinion in Australian ornithology: a traditional school using a purely taxonomic concept and another embracing a concept having both taxonomic and evolutionary connotations. It is concluded that the emphasis should be placed on the study of geographical variation and the determination of zones of secondary hybridization rather than on the application of a trinomial to every distinguishable population.