Increasingly questions are bring raised about the ability of many current health reforms to address the challenges that are facing health systems. We investigate this situation by exploring the role of professionalism in the delivery of health services. In contrast to the dominant approach of considering professionalism as a social phenomenon, professionalism is considered as primarily a task-related phenomenon. The characteristics of the task are identified as being high levels of uncertainty and complexity. These characteristics are shown to lead naturally to the key social features that typify professionalism. Hence, the close link between professionalism and the nature of the task is argued. However, health reforms threaten professionalism. They have been based on considerable dissatisfaction with the performance of professionals as well as the emergence of a number of new challenges. In addition, the reforms have been developed without significant consideration of the central role that professionalism has played, and reformers have adopted a simplified view of the task. Thus, the centrality of professionalism has intrinsically been downgraded. However, this simplification can be shown to be inconsistent with the realities and complexities of health service provision, and thus the downgrading of professionalism is unwarranted. This inconsistency generates many of the conflicts and contradictions being reported. The future of health service reform depends on an effective understanding of the nature of the task, recognition of the central role of professionalism and the development of professional and organisational structures that support each other.