This paper investigates the potential threat to medical dominance posed by the addition of pharmacists as prescribers in the UK. It explores the role of prescribing as an indicator of professional power, the legitimacy and status of new pharmacist prescribers and the forces influencing professional jurisdictional claims over the task of prescribing. It draws upon 23 interviews with pharmacist supplementary prescribers. Data suggest that the legitimacy of pharmacists as prescribers, as experienced in the workplace, has been aided by: (1) blurred definitions of prescribing; (2) the emphasis on new prescribers' competence urging pharmacist prescribers to limit their areas of clinical practice; and (3) a team approach to patient management. Competence, self-limitation on practice and the benefits of team working as part of the ideology of patient safety were thus an important influence on pharmacists' jurisdictional claim over prescribing. While pharmacists have successfully negotiated a role for themselves as prescribers, medicine has retained its high status, relative to other health professionals and with patients; it controls the knowledge base relevant for prescribing practice and has managed to develop an 'overseer' role over the process of prescribing. Prescribing, as an indicator of medicine's autonomy of control over their work and professional status, has changed. Yet the extent to which new prescribers have been able to threaten the professional dominance of medicine is debatable.