Abstract： Background:Uterus didelphys and blind hemivagina associated with ipsilateral renal agenesis are collectively known as Herlyn-Werner-Wunderlich syndrome (HWWS).In the literature,the syndrome often appears as a single case report or as a small series.In our study,we reviewed the characteristics of all HWWS patients at Peking Union Medical College Hospital (PUMCH) and suggested a new classification for this syndrome because the clinical characteristics differed significantly between the completely and incompletely obstructed vaginal septum.This new classification allows for earlier diagnosis and treatment.Methods:From January 1986 to March 2013,all diagnosed cases of HWWS at PUMCH were reviewed.A retrospective long-term follow-up study of the clinical presentation,surgical prognosis,and pregnancy outcomes was performed.Statistical analyses were performed using SPSS,version 15.0 (IBM,Armonk,NY,USA).Between-group comparisons were performed using the x2 test,Fisher's exact test,and the t-test.The significance level for all analyses was set at P ＜ 0.05.Results:The clinical data from 79 patients with HWWS were analyzed until March 31,2013.According to our newly identified characteristics,we recommend that the syndrome be classified by the complete or incomplete obstruction of the hemivagina as follows:Classification 1,a completely obstructed hemivagina and Classification 2,an incompletely obstructed hemivagina.The clinical details associated with these two types are distinctly different.Conclusions:HWWS patients should be differentiated according to these two classifications.The two classifications could be generalized by gynecologists world-wide.