SATO, S., YAMADA, M., MIYAZAKI, Y., MATSUDA, K., KANNO, A., ISHII, M., OHORI, H. and TOYOTA, T. Relationship between Molecular State of Serum HBV-DNA and Clinical Features of Hepatitis B Virus Carriers. Tohoku J. Exp. Med., 1993, 171(4), 309-317-Molecular species of serum hepatitis B virus (HBV)-DNA in HBV carriers were classified by Southern blot hybridization into three types; type I with two bands of 4.0kb and 3.2kb, type II with the two bands of type I plus the smear between 4.0kb and 3.2kb, and type III with a broad band below 4.0kb. A total of 51 HBV carriers were classified into three groups (group I, n=19 with type I; group II, n=12 with type II; and group III, n=20 with type III). Serum aminotransferase levels of group I were significantly lower than those of groups II and III. Liver pathology revealed that 18 of the 19 (94.7%) group I patients showed nonspecific reactive hepatitis (NSRH), while 11 of the 12 (91.7%) group II patients and 19 of the 20 (95.0%) group III patients showed chronic persistent hepatitis (CPH) or chronic active hepatitis (CAH). Immunohistochemical study showed that hepatitis B core antigen (HBcAg) was localized in the nucleus of hepatocytes in most of patients with type I while it was localized in both the nucleus and cytoplasm in those with types II and III. Since the smear between 4.0kb and 3.2kb is specifically found in groups II and III, HBV-DNA with this smear may be related to active hepatitis.