Factors contributing to the development and maintenance of the Hyperventilation Syndrome (HVS) are presented. Studies on the effectiveness of treatment methods are discussed. Subsequently, the procedures of a behavioural group treatment for HVS-patients are described. Goals in the treatment are: learning to cope adequately with hyperventilation complaints and its' accompanying anxiety, discovering factors in one's behavior which maintain the complaints and the anxiety, and learning to cope with stressful situations. Results show that this treatment of 17 sessions was sufficient for about half of the 15 patients. The other half continued treatment individually or with their partner.