Objective To study the levels of Urotensin Ⅱ(UⅡ)in the different grades of obstructive sleep apnea syndrome(OSAHS)patients and the correlation of UⅡ to OSAHS.Methods Seventy-five OSAHS patients were divided into five groups according to light,medium,serious AHI,simple snorers and normal part;UⅡ levels of the plasma were measured and correlation analysed.Results UⅡ levels:light group(10.44?4.12)ng/L、medium group(38.55?15.8)ng/L、serious group(94.78?19.63)ng/L、simple snorers group(1.37?0.42)ng/L、normal group(1.14?0.65)ng/L.Statistic difference existed among these groups(P