A major difficulty in assessing incidence and prevalence of occupational diseases among the workforce employed on South African mines is the lack of epidemiological data. Published and unpublished data were collated and analysed for the period 1915-1988 in order to provide insights into occupational disease trends. Using proxies for incidence rates, it was demonstrated that the rates of silicosis and tuberculosis were likely to be high. In the case of silicosis among black miners, disease was contracted in a relatively short period on average. The stabilisation of the black workforce on the mines, which started in 1975 and continues, is an important factor likely to lead to an increase in occupational disease rates. Recommendations for improved data reporting and research are made, in particular the need to identify occupational groups at high risk and the calculation of prevalences.