The purpose of this paper is to describe a new tick of the genus Ornithodoros Koch, from South Africa. Specimens were received through the courtesy of Dr Zumpt of the South African Institute of Medical Research, after being collected from the burrow of a striped mouse, Rhabdomys pumilio (Sparrman), near Cathcart, Cape Province, in April 1952. Interest in the ‘burrow haunting’ Ornithodoros of Africa has increased in recent years, because certain of these ticks have been found to transmit spirochaetes of rodents and other small mammals. These spirochaetes may be evolutionary precursors of those that infect man, and cause the well-known sporadic relapsing fever of tropical Africa. Two live Ornithodoros larvae from the burrow were emulsified and inoculated into a white mouse but no spirochaete was isolated (Zumpt, personal communication).