The reason for increased cardiac mortality in panic disorder has not been precisely identified, but possibly is due to chronic activation of the cardiac stimulant (sympathetic) nerves, which may predispose the individual with panic disorder to disorders of cardiac rhythm and coronary artery spasm. The uniqueness of this study lies in its comprehensive evaluation of a psychobiological approach to the treatment of panic disorder using change in biological, behavioural and psychological variables as criteria for efficacy. 50 patients aged between 18 and 60 years will be recruited; both males and females. They will be treated with either cognitive behavioural therapy (CBT) or SSRI (selective serotonin re-uptake inhibitor) antidepressants or a combination of both.