Some challenges facing occupational epidemiology in developing countries are outlined in this case study of agriculture drawing on Southern African research. These include the characterization of exposures in resource- and data-poor environments typical of developing countries, the assessment of outcomes where cross-cultural and socio-environmental confounders may be substantial obstacles, and the impact of environmental exposures on workplace health. Traditional assignment of low priority to the chronic effects of low-dose exposures relative to acute morbidity in developing countries must be critically examined, as must the gender bias of much occupational epidemiology in agriculture. Advocacy issues involving child labor and the ethics of research among vulnerable groups deserve rigorous attention. It is argued that, if occupational epidemiology is to have meaningful impact on the health of the most marginalized groups of workers in developing countries, it must redefine itself in terms of a public health approach. The boundaries of epidemiologic inquiry need to be broad, and amenable to interfacing with policy research, using qualitative methods and participatory approaches. More so than in order industrial settings, epidemiologists must move from research to practice, seeking to take action where interventions are needed, and to evaluate such actions.