Systemic lupus erythematosus (lupus) is a complex condition characterised by wide ranging symptoms that are sometimes transient in nature. This makes recognising and diagnosing lupus particularly challenging for both patients and practitioners. The diagnostic process in this condition is a complex interplay between the boundaries of knowledge and power, control, integrity and legitimacy, which are (re)constructed and (re)negotiated between contemporary medicine, the patient and practitioner. Utilising data generated through a qualitative research design, this article illustrates some of the challenges lupus presents in the clinical encounter. We argue that the diagnosis of lupus is not a clinical event or a ‘diagnostic moment’. Rather, it constitutes a journey in and of itself, one which, for many of the respondents in this study, has no diagnostically satisfying conclusion. We conclude that uncertain diagnoses, such as lupus, illustrate the extent of both embodied and clinical doubt in, what might be termed, contemporary conditions and, concomitantly, throw into sharp relief the nature of the diagnostic process. This process, in the context of lupus, and other uncertain conditions, generates, we would argue, a sense of diagnostic vertigo.