Abstract: Objective To investigate the situation of TTV infecting in various crowds in Shanghai and to explore the high-risk crowd and spreading way of TTV.Methods Applying semi-nested PCR to test TTV DNA and picking out some PCR outcome (249bp)of positive sample to deter mine the nucleotidesequence.Results Eight groups counting to 473 are examined,sixty patients are non A~G hepatitis,102 patients are A~G hepatitis,55 patients are hemodialysis,38 children are blood disease,68 healthy men and 50 patients are venereal disease,vein freak-out and cancer of the liver.The gross masculine rate of TTV DNA is 28.33% (134/473).The masculine rate fluctuates between 17.64% and 50%.The mascline rate of vein freak-out is 50%(25/50)and venereal disease is 36%(18/50),both of which have the no table difference(χ²=14.01,P<0.001,χ²=5.12,P>0.05)from the healthy men(17.64%).The difference of masculine rate in other group has no statistics meaning.Comparing the group of intestines infecting(A,E hepatitis)and the group of blood infecting(vein freak-out,blood disease,hemodialysis and B,C hepatitis),the corresponding masculine rate of which is 25.49% and 32.17% and has no notable difference(χ²=0.46,P>0.05).The sequence result of spreading outcome in 20 masculine samples shows that there are 15 samples which the isogenous of nucleo tide sequence and Japanese strain(N22)is higher than 85% and 5 samples lower than 85%.Conclusion The research proves that the infection of TTV is rather comprehensive in Shanghai,in which the vein freak-out and venereal disease are high-danger crowd and there maybe exists spreading way of sex contact and non-hematogenous dissemination besides blood infection.TTV is in carrying state in crowd and may be a poor nosogenetic virus.The aberrance of TTV ototoxicosis strain is in existence in Shanghai.