The presentations of sympathetic hyperactivity in OSA include hypercatecholaminemia and elevated sympathetic tone of peripheral nerve. Hypercatecholaminemia is known for attributing to the development of cardiovascular diseases. Our data showed plasma levels of both epinephrine and norepinephrine were higher in OSA patients than in control subjects. And the elevated catecholamine could go down after one-month CPAP treatment. Meanwhile, our data also showed the plasma levels of catecholamine were highly correlated with serum levels of TNF.