Objective:To compare clinical and pathologic manifestation between patients with idiopathic IgA nephropathy (IgAN) accompanied by metabolic syndrome (IgAN-MS) and IgAN-non-MS and to investigate the impact of MS on IgAN. Methods:A total of 453 patients with renal biopsy-proven idiopathic IgAN from Jan. 2006 to Jun. 2012 in Wuxi People’s Hospital were enrolled in this study. Then 87 patients were assigned to the IgAN-MS group and other 366 patients were assigned to the IgAN-non-MS group. A comparative analysis of clinical and pathological data between these two groups was performed. Results:Urine protein, serum creatinine in the IgAN-MS group were significantly higher than those in the IgAN-non-MS group(P < 0.05). Pathological changes in the IgAN-MS group were significantly more severe than those in the IgAN-non-MS group(P < 0.05). eGFR was negativly correlated with urine protein of 24 hours, mean arterial pressure,age, body mass index, and serum triglyceride, while urine protein of 24 hours was positive correlated with fasting blood-glucose, body mass index, serum triglyceride and albumin,LDL-C and urine acid by Pearson correlation analysis. There were positive relationship between MS and Lee’s classification(or damage index in Oxford classification). Conclusion:MS may be an important risk factor for IgAN progression. The factors of MS could aggravate renal damage.