Objective: Purpose of the study is to develop an auxiliary tool that can be used by experts working in the clinical settings for psychological support processes to adults diagnosed with simple phobia. In that realm, one another related aim is also to evaluate the effectiveness of the developed tool via behavioral and physiological measurements. Method: Eleven participants diagnosed with specific phobia (7 females (X) over bar age=38.57, SD=8.89; 4 males (X) over bar age=41.75, SD=13.07) by mental health specialist were exposed to virtual reality scenarios in a systematic desensitization manner. There were 6 person with cynophobia, 2 with arachnophobia, 1 with acrophobia and 2 with claustrophobia. Each of four phobia scenario sessions consisted of diffferent number of stages to be completed. None of the participants were received any drug medication for phobia before and also during the study. In addition to physiological meaurements like galvanic skin response (GSR) and heart rate (HR), subjective units of distress scale (SUDS) measurements were also taken before and after exposure to each stage as dependent variables. To compare different phobia scenarios, minimum, maximum and peak-to-peak amplitude values of the first and last exposure to the most feared stimuli for physiological records and first and last exposure SUDS values again for the most feared stimuli were analyzed with Wilcoxon Signed Rank Test. Results: The most fear/anxiety procuding stimuli comparisons for the first (pre-test) and the last (post-test) exposures in SUDS, GSR and HR measurements indicated that there was significant decrements in post-test measurements with respect to the ones for pre-tests. Discussion: Analyses of behavioral and physiological measurements obtained from the participants showed that the learned-fear-responses have a tendency to extinct after being exposed to the relevant stimuli virtually. Thus, virtual reality applications can be effectively usable in the treatment of specific phobias.