Abstract: Abstract Obejective: To explore the correlation of respiratory drive with orexin A in COPD patients. Methods: Pulmonary function test was performed in 30 patients with stable COPD and 20 normal healthy adults. The level of plasma orexin-A was measured with a radioimmunoassay kit. The correlation of orexin A with BMI, age, BDI, FEV1, FVC, FEV1/FVC, MEP, MIP, P0.1 in COPD patients was analyzed. Results: The plasma orexin-A levels in patients with COPD group （1.87±0.43）ng/L was higher than those in the control group （1.49±0.19）ng/L, P< 0.01. Plasma orexin-A levels in patients with COPD correlated negatively with FEV1（r=-0.389，P<0.05），and correlated positively with P0.1（r=0.728，P< 0.01）.Conclusions: The plasma orexin A in COPD patients are increased which may be caused by smoking and hypercapnia. Orexin A may play a crucial role in the regulation of respiratory drive in COPD patients.

Key words: pulmonary disease, chronic obstructive, respiratory function tests, respiratory center, orexin-A