Treatment for acute hepatitis B is recommended in order to reduce the risk of progression to fulminant hepatitis and the need of OLT. We report our experience on treatment with high dose lamivudine, in patients with severe acute HBV infection. The diagnosis was based on clinical and virological findings and exclusion of other known causes of liver damage. The decision to treat was based on the prolongation of INR together with increasing values of bilirubin and ALT. Four patients received Lamivudine 200 mg/daily until clearance of serum HBV-DNA and then 100 mg/daily until clearance of HBsAg and appearance of anti-HBs antibodies. One patient received 100 mg/daily because of chronic renal impairment. The median period of hospitalization was 13 days, and none of the patients had complications, related either to underlying disease or to therapy. The complete normalization of serum transaminases and bilirubin occurred on average after 5.5 weeks and 3 weeks respectively. All patients cleared serum HBV-DNA within three months, lost HBeAg and HBsAg and seroconverted to anti-HBe; four patients developed anti-HBs at a protective titre. Early antiviral treatment attenuates the clinical and biochemical impairment leading to fast healing and promoting complete recovery.