Objective To observe the changes of urinary microalbumin(UMA),and explore the relation between early impairment of renal function and level of UMA in patients with obstructive sleep apnea hypopnea syndrome(OSAHS).Methods OSAHS patients(n=67)and healthy control subjects(n=82).Then body parameter,serum creatinine(SCr),blood urea nitrogen(BUN),glomerular filtration rate(GFR)and UMA were determined in both groups.Furthermore,linear correlation was performed between UMA and body parameter,SCr,BUN,GFR and sleep-breathing parameters of patients with OSAHS,respectively.Results UMA level was higher in OSAHS patients than that in control subjects(P＜0.01).UMA level in OSAHS patients was correlated positively with body mass index(BMI),apnea hypopnea index(AHI),percentage of sleep time below 90% oxygen saturation (SaO2＜90%)and percentage of sleep time the total duration of apnea/hypopnea,respectively,and those were correlated negatively with the lowest SaO2 and the average lowest SaO2 respectively,but those had no correlativity with age,stature,waistline,neckline,SCr,BUN and GFR(P＞0.05).Conclusions UMA level increases in patients with OSAHS.The detection of microalbumin in urine is helpful in early diagnosis in OSAHS renal damage patients.