Sixty‐four patients with chronic hepatitis B who were treated with interferon‐α (recombinant IFN‐α‐2a in 9 patients, recombinant IFN‐α‐2b in 50 patients and lymphoblastoid IFN‐α‐n1 in 5 patients) in protocols conducted at the Liver Diseases Section of the National Institutes of Health between 1984 and 1986 were observed with sequential determinations of serum ALT levels, HBsAg and serological markers of hepatitis B virus replication (HBeAg, hepatitis B virus DNA polymerase, hepatitis B virus DNA by blot hybridization and hepatitis B virus DNA by polymerase chain reaction). Among the 64 treated patients, 23 responded to interferon treatment with loss of HBeAg and improvement in serum ALT. Three patients (13%) relapsed, all within the first year of follow‐up. The remaining 20 patients continued to have no detectable HBeAg or hepatitis B virus DNA (dot blot) in serum during follow‐up of 3 to 7 yr (mean = 4.3 yr), although 3 patients had minimal elevations of serum ALT. Thirteen patients (65%) lost HBsAg between 0.2 and 6 yr (mean = 3 yr) after loss of HBeAg. Although none of the 20 patients had detectable serum hepatitis B virus DNA (dot blot), all 7 patients with persistent HBsAg had detectable serum hepatitis B virus DNA by the polymerase chain reaction. Sequential testing in HBsAg–patients indicated the serum hepatitis B virus DNA usually became undetectable by the polymerase chain reaction at about the time of loss of HBsAg. Only 2 of 13 HBsAg– patients had hepatitis B virus DNA detectable in serum by the polymerase chain reaction. Copyright © 1991 American Association for the Study of Liver Diseases