Cognitive-behavioural models of body dysmorphic disorder (BDD) suggest that mirrors can act as a trigger for individuals with BDD, resulting in a specific mode of cognitive processing, characterised by an increase in self-focussed attention and associated distress. The aim of the current study was to investigate these factors experimentally by exposing participants with BDD (n=25) and without BDD (n=25) to a mirror in a controlled setting. An additional aim was to ascertain the role of duration of mirror gazing in the maintenance of distress and self-consciousness by manipulating the length of gazing (short check vs. long gazing). Findings demonstrated that contrary to what was predicted, not only participants with BDD, but also those without BDD experienced an increase in distress and self-focused attention upon exposure to the mirror. In addition, people without BDD, unlike those with BDD, experienced more distress when looking in the mirror for a long period of time as opposed to a short period of time. This lends some support to the idea that, for people with BDD, gazing in a mirror, regardless of duration, might act as an immediate trigger for an abnormal mode of processing and associated distress, and that this association has developed from past excessive mirror gazing. Further theoretical implications of these findings, as well as subsidiary research questions relating to additional cognitive factors are discussed.