Background: The enhancement of quality of life (QOL) is a principal health care objective. Surprisingly, few studies have investigated this outcome in ANCA associated vasculitis (AAV), a complex chronic disease. Existing studies have, however, identified fatigue as a specific problem amongst this population. Although its aetiology is unknown, there is evidence, from other populations, to support a neural basis for this symptom. Aims: This study aimed to characterise QOL and its determinants amongst patients with AAV. A secondary study examined the association of AAV related fatigue with alterations of the brain. Methods: An AAV case-control study was conducted, incorporating a comparison and within-case analysis, using two groups of population and chronic disease controls. All participants completed a questionnaire comprising measures of QOL and putative determinants of QOL impairment. Concurrently, putative clinical determinants were collected from cases. The secondary study recruited AAV cases based on fatigue status. A further group with idiopathic fatigue was recruited from the general population. All subjects underwent magnetic resonance (MR) brain scanning incorporating structural and physiological imaging. Results: Compared to population controls, cases were substantially more likely to report low QOL and levels were equable to disease controls. Potentially modifiable biological and psycho-social factors were independently associated with poor QOL, of which fatigue was found to be of principal importance. In the secondary study, structural and physiological differences were observed between AAV patients with and without fatigue, as well as fatigued population subjects. Conclusions: AAV patients experienced significant QOL impairment. A bio-psychosocial approach to AAV health care is likely to improve QOL outcomes, although a better understanding of specific mechanisms is necessary to fully manage these problems. MR techniques have suggested a neural basis for AAV related fatigue. In the future they may help delineate the mechanisms of fatigue and consequently improve QOL in AAV.