Reinfection with hepatitis B virus (HBV) after liver transplantation is nearly universal in patients not receiving immunoprophylaxis. Because reinfection reduces graft and patient survival, treatment of recurrent infection is important. Interferon alfa (IFN-α) is an effective therapy for chronic hepatitis B infection in immunocompetent patients, but its efficacy in transplant recipients has not been established. Fourteen liver transplant recipients with recurrent hepatitis B infection (hepatitis B surface antigen [HBsAg] positive in serum; hepatitis on biopsy) were treated with IFN-α2b (Intron A; Schering Inc, Kenilworth, NJ) 3 million units (MU) three times weekly for 23.5 weeks (median, range 4 to 41). The primary endpoint was loss of HBV DNA by the b-DNA assay (a virological response). Before treatment, all patients were HBV DNA positive and 9 were hepatitis B e antigen (HBeAg) positive. Pretreatment HBV DNA levels were 6,760 MEq/mL (median, range 2.0 to 11,888 MEq/mL). HBV DNA levels decreased significantly with treatment (P = .03). Four patients had a complete and sustained virological response. Virological responses did not consistently correlate with biochemical response because of concomitant hepatitis C. Two patients had a serological response; 1 lost HBeAg, another lost HBeAg and HBsAg. All responders remained HBV DNA negative in follow-up (mean, 32 months; range, 23 to 40), but 1 patient required retransplantation for cirrhosis. Of the nonresponders, 1 patient required retransplantation for chronic rejection, 3 required retransplantation for recurrent hepatitis B, 3 died with recurrent hepatitis B, and 3 are alive and remain HBV DNA positive. IFN-α can induce a sustained serological (14%) and virological response (29%) in liver transplant recipients with recurrent HBV infection. Copyright © 1996 by the American Association for the Study of Liver Diseases.