Intolerance of uncertainty (IU) is a transdiagnostic process contributing to the maintenance of anxiety disorders, and is a potential target for treatment. Recent literature has investigated IU as a cognitive process underpinning pathological fear and anxiety in Anorexia Nervosa (AN). The current study was designed to examine trait and state IU, and their relationship to restrictive eating disorder symptoms, anxiety, worry, cognitive rigidity and eating behaviour.