The widespread use of artificial insemination in the pig industry has provided breeders with access to genetic material from superior boars from around the world. Selection of parent stock is based on estimated breeding values (EBVs), which are regularly computed in all countries performing genetic evaluations. The purpose of this study was to evaluate the value of foreign sires in the South African (SA) pig industry by comparing the on-farm performances of progeny for average daily gain (ADG), feed conversion ratio (FCR) and back fat thickness (BF) from progeny sired by USA and Canadian born sires to the performance of progeny from local sires and to progeny with paternal USA grandsires (F1-US sires). The breeds analysed comprised of Duroc, Landrace and Large White pigs. Males outperformed females for all traits measured (P <0.0001). Large differences (P <0.0001) were observed between on-farm performances which had similar climatic regions for all traits except Duroc BF (P <0.05). Farm differences were consequently attributed to management rather than environmental influences. The effect of country was significant (P <0.05) in all the models tested with the USA-sired progeny having the best overall performance. However, as measured by a stepwise R2, country remained the smallest contributor to variation across all models (except BF in Landrace), with farm, sex and year-season contributing larger portions to the variation observed in the on-farm performances of progeny. These results indicate that most of the variation observed could be attributed to differences in farm as explained by management, rather than superiority of the imported boar semen.