Lay health workers are key to achieving universal health-care coverage, therefore measuring worker attrition and identifying its determinants should be an integral part of any lay health worker programme. Both published and unpublished research on lay health workers has largely focused on the types of interventions they can deliver effectively. This is an imperative since the main objective of these programmes is to improve health outcomes. However, high attrition rates can undermine the effectiveness of these programmes. There is a lack of research on lay health worker attrition. Research that aims to answer the following three key questions would help address this knowledge gap: what is the magnitude of attrition in programmes? What are the determinants of attrition? What are the most successful ways of reducing attrition? With community-based interventions and task shifting high on the United Nations Millennium Development Goals' policy agenda, research on lay health worker attrition and its determinants requires urgent attention.