Personal autonomy is widely valued. Recognition of its vulnerability in health care contexts led to the inclusion of respect for autonomy as a key concern in biomedical ethics. The principle of respect for autonomy is usually associated with allowing or enabling patients to make their own decisions about which health care interventions they will or will not receive. In this paper, we suggest that a strong focus on decision situations is problematic, especially when combined with a tendency to stress the importance of patients' independence in choosing. It distracts attention from other important aspects of and challenges to autonomy in health care. Relational understandings of autonomy attempt to explain both the positive and negative implications of social relationships for individuals' autonomy. They suggest that many health care practices can affect autonomy by virtue of their effects not only on patients' treatment preferences and choices, but also on their self-identities, self-evaluations and capabilities for autonomy. Relational understandings de-emphasise independence and facilitate well-nuanced distinctions between forms of clinical communication that support and that undermine patients' autonomy. These understandings support recognition of the value of good patient-professional relationships and can enrich the specification of the principle of respect for autonomy.