Lucilia sericata (Meigen, 1826) and Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae: Luciliinae) have medical, veterinary and forensic importance. Knowing their distribution in South Africa would allow more effective management and utilisation of these flies. Their predicted geographic distributions in South Africa were modelled using maximum entropy analysis of selected climatic variables. The most important environmental variables in modelling the distributions were the magnitude of monthly rainfall and the magnitude of the monthly maximum temperature for L. sericata and the seasonal variation in monthly mean humidity and magnitude of monthly rainfall for L. cuprina. A clear geographical bias was shown in museum records and supports the need for focused surveys. There was no correlation between the predicted distribution of L. cuprina and sheep farming in South Africa, nor between the predicted distribution of L. sericata and human population density. Although their patterns of occurrence differed, both species are widely distributed in South Africa and therefore one cannot identify these flies by locality alone — morphological or molecular identification is necessary.