Immunisation is a cornerstone of preventive medicine. The prospects for continuation of this position are outstanding, since the medical intervention has been deemed as cost-effective in major publications on global disease prevention priorities. Recently, the financial foundations of global immunisation efforts have been strengthened considerably through the establishment of a large fund with a viable organisational underpinning. Routine vaccination programmes, usually known as Expanded Programme on Immunisation (EPI), now have an almost world-wide coverage. Despite high coverage levels, there have always been parents with doubts about the efficacy, safety and necessity of childhood vaccinations on offer. Although usually acceptance of vaccination was and is the general pattern, individual refusal and public resistance have been documented. This article focuses on the forms and implications of public doubts about vaccines and vaccinations in industrialised and in developing countries. Using, among other sources, material from the Social Science and Immunisation Project it explains how such reactions must be understood in context. It highlights different forms and trajectories of non-acceptance of vaccinations and discusses how policy makers and programme managers could address these issues.