In this paper, an attempt is made to give patient autonomy added conceptual clarity. A concept of patient autonomy grounded in both negative and positive freedoms is defended. Amartya Sen's capabilities approach is used as a conceptual framework in which patient autonomy and fairness are defined compatibly. It is argued that in a socially fair healthcare system, everyone should have at least the degree of patient autonomy that affords access to those healthcare services necessary for survival and a minimally adequate level of quality of life, consistent with each person's naturally endowed health characteristics.