Dairy cattle semen imported from January 1979 to June 1989 consisted of 72% Holstein-Friesian, 13.6% Jersey, 11.5% Ayrshire and 2.8% Guernsey semen. There has been a significant increase in the importation of Holstein-Friesian semen and, to a lesser extent, in that of Jerseys since 1986. An increasing amount of North American Holstein semen was imported during the study period. Almost three-quarters of the imported Holstein-Friesian semen came from only two Holstein lines, viz. Ivanhoe and Chief. Ivanhoe was succeeded by his grandson Elevation and Chief by his son Valiant, which also became successful lines. Owing to semen importations, the Holstein breed of the USA has an increasingly strong influence on the Holstein-Friesian breed in South Africa. The selectiveness of the South African importers by importing semen of mainly two lines could possibly narrow the genetic base of the South African Holstein-Friesian breed in the future, especially if local AI bulls are also related to these two lines. It is recommended that, although standards should be kept high, semen of a wider range of lines should be imported.