Recent research presents Augmented Reality Exposure Therapy (ARET) for treatment of phobia of cockroaches as a potentially effective technique. However, to the authors' knowledge no studies have been published concerning the Human-Computer-Interaction issues of such a system. The aim of this paper is to report some preliminary data on how patients, therapists and an Augmented Reality system collaborate and interact during the therapeutic process. The results show that the therapeutic process is distributed between individuals (patient and therapist) and artifacts (e.g. AR cockroaches, a computer screen, a Head Mounted Display (HMD), a keyboard, a swatter and therapists' notes on paper). The results are discussed in terms of possible improvement of the ARET system.