Sera from 3012 rodents of 24 species captured in South Africa during the period 1972-81 were tested for antibody to the Fraction 1 antigen of Yersinia pestis by passive haemagglutination. Antibodies were found in seven (0.23%) rodents of three species. These were Desmodillus auricularis and Tatera brantsii in the northern Cape Province and Rhabdomys pumilio in the eastern Cape Province. Rodents were found positive in 1972, 1974, 1975 and 1979, indicating that plague continues to circulate in rodent populations apparently without causing human cases. The significance of the results is discussed in relation to plague outbreaks in neighbouring countries and to the 1982 outbreak in South Africa.