Objective To investigate the levels of serum visfatin in adult male patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). Methods Seventy-three adult males with habitual snoring received polysonmographic examinations. Based on apnea hypopnea index (AHI), patients were divided into control group (AHI<5/h, n=13), mild OSAHS group (AHI 5-20/h, n=14), moderate group (AHI 21-40/h, n=15) and severe OSAHS group (AHI>40/h, n=31). The serum visfatin levels were measured by ELISA. Results ①There were significant differences in the serum visfatin levels among groups, and the serum visfatin levels increased with the severity of OSAHS [（0.23±0.11） ng/mL, （0.24±0.19） ng/mL, （0.29±0.24）ng/mL and （0.48±0.32） ng/mL, F=4.704，P=0.005）]. The serum visfatin level in severe OSAHS group was significantly higher than those in control group, mild OSAHS group and moderate group (t=2.751，P=0.009；t=2.563，P=0.014；t=2.014，P=0.05). ②Serum visfatin level was positively correlated with AHI, obstructive sleep apnea-index (OAI), micro-arousal index, duration of lowest oxygen desaturation and percentage of the total recorded time spent below 90% oxygen saturation level (TS90)(P<0.01), but was negatively correlated with lowest pulse oxygen saturation (LSPO2)(r=－0.435, P<0.01). ③Partial correlation analysis revealed that the serum visfatin level was positively correlated with OAI (r=0.253, P=0.033) after adjustment for body mass index (BMI) and neck circumference. ④Analysis of receiver operating characteristic (ROC) curve indicated that the cut-off value of serum visfatin was 0.273 ng/mL, and the sensitivity and specificity for differentiating mild and moderate OSAHS from severe OSAHS were 77% and 64% respectively. The area under the ROC curve was 0.733, and 95%CI was 0.609 to 0.858 (P=0.001). Conclusion Serum visfatin level increases with the severity of OSAHS in adult males, and the elevation of serum visfatin is related to the prevalence of OSAHS.