Objective To study the association of MYH9 gene single nucleotide polymorphism (SNP) with clinical manifestation,pathology and prognosis of IgA nephropathy (IgAN) patients of Han nationality population in Inner Mongolia Autonomous Region.Method One hundred and forty-eight IgAN patients proven by biopsy were enrolled in the study.Fifty-six patients were followed up for 1-97 months.DNA was extracted from the peripheral blood of above patients.PCR restriction fragment length polymorphism (RFLP) assay was used to detect the single nucleotide polymorphisms of MYH9 gene Rs3752462,Rs4821480 sites.Association of different genotypes with clinical features,pathology and prognosis im patients with IgA nephropathy was examined.Result (1) Rs3752462 site was consistent with Hardy-Weinberg equilibrium,while Rs4821480 site did not meet the Hardy-Weinberg equilibrium.(2) IgAN patients with MYH9 gene Rs3752462 site TF genotype had lower systolic blood pressure as compared to those with CC +CT genotype (P＜0.05).There were significant differences in systolic blood pressure,diastolic blood pressure and age between patients with Rs4821480 site GG genotype and patients with TT or GT genotype (P＜0.05).There were no significant differences in Scr,Ccr,plasma albumin,hemoglobin,microscopic hematuria,proteinuria,pathological HASS classification,pathological lesion among Rs4821480 site GG,TT,GT genotypes.(3) Kaplan-Meier survival analysis revealed the time from renal biopsy to renal function decline was shorted in patients with Rs3752462 site CC genotype and Rs4821480 site TT genotype.Conclusions C allele of MYH9 gene Rs3752462 site is an independent risk factor of high blood pressure damage in IgAN patients.Polymorphism of 3 genotypes of MYH9 gene Rs4821480 site is associated to the prognosis of patients.Carrying Rs3752462 site C allele and Rs4821480 site T allele may affect the prognosis of patients.