Introduction: This study aims to examine effectiveness of Meta-cognitive therapy on Cognitive Attentional Syndrome (CAS) & Cognitive Emotion Regulation strategies of patients suffering from Generalized Anxiety Disorder (GAD).Method: 8 patients (5 Females) from the clients of psychiatric clinic of Baqiyatallah hospital, were selected through available sampling, matched together and then divided into 4 groups (Meta-cognitive therapy, Meta-cognitive therapy combined with medications, medications & Control). Patients receiving Meta-cognitive therapy and residual ones were examined respectively 5 & 3 times by Cognitive Attentional Syndrome Scale (CAS-1) and the short form of Cognitive Emotion Regulation Questionnaire (CERQ). To analyze the data, indexes of process changes, slope and interpretation of ups & downs in charts were employed.Result: After treatment, scores of patients who received Meta-cognitive therapy showed decrease in CAS & maladaptive Cognitive Emotion Regulation strategies (Self-blaming, Rumination, Catastrophizing); additionally, in some adaptive Cognitive Emotion Regulation strategies (Positive refocusing, Refocusing on planning, Positive Reappraisal) an increase was observed.Conclusion: Meta-cognitive therapy via targeting directly mechanisms of pathological worry, can be appropriate choice for treatment of Generalized Anxiety Disorder.