The need for evidence on postdoctoral research fellows, or ‘postdocs’, has become increasingly evident globally, as many countries, including South Africa, lack information on these researchers. We used existing sources of quantitative data to provide a longitudinal profile of postdocs at South African public universities. These sources include national research-and-development surveys and data from the national Higher Education Management Information System. Our focus was on postdocs’ representation and research intensity (i.e. time spent on research) within the national research system, as well as on two key demographic features, namely nationality and gender. We draw comparisons with findings reported for other countries to situate our results within the global science system. Interpretation of our results leads us to comment on global and national developments and policies relevant to postdocs.