Abstract Objective：To investigate the plasma homocysteine level in patients with obstructive sleep apnea hypopnea syndrome and its clinical significance. Method：Hcy levels were determined by enzyme-linked immunosorbent assay in 52 patients with OSAHS，54 patients with simple hypertension， 60 patients with OSAHS combined with hypertension and compared with normal control group， the test results and sleep apnea monitoring index were given correlation analysis. Result：Plasma Hcy level of the simple OSAHS group was（ 19.28±6.60）μmol/L， which was significantly higher than（5.82±4.65）μmol/L of the normal control group；the pure hypertension group was（ 27.32±6.20）μmol/L，which was significantly higher than（19.29±6.60）μmol/L of the simple OSAHS group； OSAHS combined with hypertension group was（ 38.83±5.90）μmol/L，which was significantly higher than（ 27.32±6.20）μmol/L of the simple hypertension group，the differences were statistically significant（P<0.01），there was a significant correlation between Hcy level and the severity of sleep apnea and blood pressure. Conclusion：Hcy involves in the pathophysiological process of OSAHS，plays an important role in the incidence of OSAHS combined hypertension patients.
