Augmented Reality has been used in many fields, but it has not been used to treat psychological disorders. Augmented Reality presents several advantages respect to: the traditional treatment of psychological disorders and Virtual Reality treatments. In this paper we present the first Augmented Reality System for the treatment of phobia to cockroaches. Our system has been developed using ARToolkit software. It has been tested with one patient and the results have been very satisfactory. At first of the exposure session the patient was not able to approach to a real cockroach and after the exposure session using our Augmented Reality system, the patient was able to approach to a real cockroach, to interact with it and to kill it by herself. This first result is very encouraging and it demonstrates that Augmented Reality exposure is effective for the treatment of this kind of phobias.