The purpose of this study was to 1) To analyse changes in child behavior and therapist responses during play therapy. 2) To ascertain if child-centered play therapy effectively decreased the pathological characteristics of anxiety disorder. The single subject of this study was a four year old diagnosed with anxiety disorder. The case was analysed on the basis of 10 videotaped play therapy sessions. The major findings were as follows:- 1) The frequency of coded child behavior and therapist responses did not remain constant. The frequency of most coded behavior Increased at the second stage and significantly decreased during the third stage. This pattern was mirrored by the therapist`s responses to the child`s behavior. 2) The techniques of child centered Play therapy Promoted development functions such as attention span, verbal expressiveness and individuation. 3) It was confirmed that play therapy effectively decreased the pathological characteristics of Anxiety Disorder and also improved other behavior problems.