Markers of GB virus C (GBV-C), hepatitis C virus (HCV) and hepatitis B virus (HBV) were sought in sera from 1,044 cases autopsied at the Medical Examiner's Office, Tokyo Metropolitan Government. GBV-C RNA was detected in 35 (3%) cases at a frequency significantly higher (P < 0.05) than in blood donors in Tokyo (4 of 448 or 1%). Three genotypes of GBV-C provisionally designated G1, G2 and G3 were determined by selective amplification with typespecific primers, and G3 (Asian type) was detected in 31 (89%), G2 (European/American type represented by the prototype hepatitis G virus) in three (9%) and G1 (West African type represented by the prototype GBV-C) in one (3%). Antibody to HCV (anti-HCV) was detected in 116 (11%) cases and accompanied by HCV RNA in 88. HCV genotypes were I/1a in one (1%), II/1b in 55 (63%), III/2a in 17 (19%) and IV/2b in 13 (15%). Antibodies to hepatitis B virus (HBV) was detected in 335 (32%) cases and hepatitis B surface antigen in 14 (1%). Subtypes were determined in 12 of them, adw was found in seven (58%), adr in four (33%) and adyr in one (8%). GBV-C RNA was detected significantly more frequently (P < 0.01) in the cases with liver disease (9 of 70 or 13%) than in those with the other causes of death (26 of 974 or 3%). Anti-HCV was more frequent in the cases with GBV-C RNA than in those without it (15 of 35 or 43% vs. 101 of 1,009 or 10%, P < 0.001). These results indicate that infection with GBV-C as well as HCV was common, while infection with HBV was not common in the Medical Examiner's autopsy cases in Tokyo.