Nothobranchius capriviensis, new species, is described. This annual killifish inhabits seasonal pools in the area between the Zambezi and Chobe rivers and is restricted to the eastern part of the Zambezi Region (formerly the Caprivi Strip) of Namibia, in southern Africa. It is closely related to N. kafuensis, which occurs in neighboring Zambia, and can be distinguished from it by differences in male and female coloration, morphometric and meristic characters, and mtDNA. For comparison purposes, new morphometric and meristic data, and updated color pattern descriptions are provided for N. kafuensis. Consideration of biogeographical relationships suggests that these two species were derived from a common ancestor associated with a major ancient drainage system, the Paleo-Chambeshi, the middle and lower reaches of which comprised the Proto-Kafue River. The primary event that led to isolation of the Caprivi populations, and consequent divergent development, was a rearrangement of major ancient drainage, in particular that of the evolving Zambezi River, that occurred during Late Pliocene to Early Pleistocene times. In view of the very restricted distribution of N. capriviensis, and because it is here shown to be distinct from the more widely-distributed N. kafuensis in Zambia, it is suggested that its conservation status in the IUCN Red List of Threatened Species be upgraded.