ABSTRACT: BACKGROUND:The clinical outcome varies considerably in primary membranous nephropathy (pMN). Risk factors for kidney prognosis include ageing, male gender, persistent heavy proteinuria, decreased eGFR at presentation, persistent elevation of anti-PLA2R antibodies, no remission, and so on. It was controversial whether the histopathological features of pMN could predict treatment response and kidney outcome. METHODS:A retrospective study was conducted in 371 patients with biopsy-proven pMN. Pathological parameters included immunofluorescence staining, membranous Churg's stages, sclerosis, crescent, focal segmental sclerosis lesion, chronic and acute tubulointerstitial injury. The fluorescence intensity was determined: 0, negative; 1, weak; 2, moderate; 3, strong; 4, glaring. Chronic tubulointerstitial injury was graded by the involved area: 0, 0-5%; 1, 6-25%; 2, 26-50%; 3, >?50%. RESULTS:We found that patients with higher intensity of C3 staining, advanced membranous stage, and more severe chronic tubulointerstitial injury presented with higher positivity rate of anti-PLA2R antibodies, higher levels of urinary protein excretion and serum creatinine, and lower level of serum albumin. Univariate Cox regression analysis showed that severe (grade?=?3) chronic tubulointerstitial injury was a risk factor to the kidney outcome of ESKD (HR?=?61.02, 95%CI, 7.75-480.57, P ?0.05). CONCLUSIONS:We found the prognostic role of chronic tubulointerstitial injury to the kidney outcome of pMN. This study highlighted the value of kidney biopsy under the widespread usage of anti-PLA2R antibodies for diagnosis and prognosis.