Some patients choose not to attend for health care despite health concerns or an opportunity for improved health. Social norms that privilege professional expertise, and good health, deem this choice irrational. However, this paper explores how a particular version of rational choice theory suggests 'positive choices' for such non-attendance. These are cognitive and subjectively rational decisions, which are made freely with potentially positive consequences and are not social problems if respect for personal autonomy trumps obligations to others. Specifically, Boudon's 'cognitivist theory of action' is used to conceptualise nonattendance as both a rational and irrational choice, from different perspectives. Because the perspective of non-attendees has been marginalised, the paper also suggests a typology of instrumental and non-instrumental 'strong reasons' for rational non-attendance. This may help groups such as professionals to understand and accept that non-attendance can be subjectively rational, without relinquishing their own perspective that it is irrational. Acceptance of the defensibility, if not the rightness, of the perspective of non-attendees is needed to show respect for non-attendees' moral agency and to begin to repair relationships with these individuals, who may seek help from health professionals in the future. This paper explores the potential of rational choice theory to cast light on the issue of non-attendance for health care. Some patients want to attend but are denied access by real or perceived external barriers to system entry (Beck, 1997;Lewis, 1977). In the absence of such barriers, other, competent patients (potential attendees or their surrogates) 'freely' choose not to attend in at least some circumstances. This is despite their awareness or suspicion of having a health need that may benefit from attendance, or their recognition of a possible opportunity to gain improved health. This paper challenges the dominant view of the irrationality of this choice by discussing a particular version of rational choice theory that elucidates the conditions under which individuals' purposive decisions for non-attendance can be subjectively rational. This focus on individual action complements attempts to conceptualise the process of decision making through the process of decision making through social The Sociological Review, 55:3 (2007)