Evidence based medicine (EBM), which lays special emphasis on the formal gathering and synthesis of research data by systematic review and meta-analysis, is intuitively attractive as a way of determining best treatments. However, questions remain unanswered about the underlying assumptions of EBM. There is little true dialogue between its critics and its advocates, although the latter have had considerable disagreements among themselves in the correspondence columns of medical journals about the precise way in which its methods should be used. EBM medicine is in danger of becoming a new and unchallengeable orthodoxy following its own political agenda.