Performance indicators (PIs) are widely used across the UK public sector, but they have only recently been applied to clinical care. In doing so, they challenge a previously guarded aspect of clinical autonomy-the assessment of work performance. This "challenge" is specific to a primary care setting and in the general practice profession. This paper reviews the qualitative findings from an empirical study within one English primary care group on the response to a set of clinical PIs relating to general practitioners (GPs) in terms of the effect upon their clinical autonomy. Prior to interviews with GPs, primary care teams received feedback on their clinical performance as judged by indicators. Five themes were crucial in understanding GPs responses: the credibility of PIs, the growing need to demonstrate competence, perceptions of autonomy, the ulterior purpose of PIs, and the identity of the assessor of their performance. PIs are playing a key role in changing the locus of performance assessment along two dimensions: location and expertise. As the locus helps to determine the nature of clinical autonomy, it is likely to have implications for the nature of the general practice profession.