Background:The blood gas analysis data in adult patients with congenital heart disease vary with the disease-specific characteristics. For example, Fontan patients show hypocapnea and Hypoxemia. Objectives:To elucidate the mechanisms of the respiratory-circulatory relations in adult congenital heart disease patients. Method:In 129 Tetralogy of Fallot(TF) patients, 153 Fontan patients, and 36 cyanotic patients(Cy), the data of blood gas, serum norepinephrine(NE)concentration, serum BNP concentration, caridac output, pulmonary capillary wedge pressure(PCWP), central venous pressure, ventilatory capacity(VC) and FEV were examined and compared. Result:In Fontan patients hypoxemia and hypocapnea and low cardiac output were pointed out compared to TF and Cy patients(pCO2;Fontan 35.0mmHg,TF 39.6mmHg,Cy 38.2mmHg, pO2:Fontan 71.5mmHg,TF 92.5mmHg,Cy 45.3mmHg, CI:Fontan 2.48,TF 2.92,Cy 2.64 L/min/M2). The NE concentration in Fontan patients was higher than TF patients (Fontan 309.9ng/ml, TF 219.5ng/ml). VC and FEV didn’t differ in these 3 groups statistically. In TF and Cy patients the pCO2 and pO2 showed negative correlation, while in Fontan patients there were no relation. In 3 groups no relation was found between pCO2 and NE concentration. In further analysis, the hypocapnea in Fontan patients was related to Age, BSA, Cardiac index, VC. Conclusions:The characterisitics of resipiratory-circulatory state in Fontan patients are low cardiac output, hypocapnea, hypoxemia, elevated NE concentration, lower VC, however, the hypocapnea is not related to pO2, the norepinephrine concentration, and PCWP, which have been considerd as resipiratory driving factors in adult heart failure patients. In Fontan patients, there might be more complexed mechanisms of respiratory-circulatory relation.