We report a case series of three HBeAg positive and five HBeAg negative patients (7 males, mean age 50.6 +/- 14.6 years) with chronic HBV infection experiencing sero-conversion after treatment with entecavir (0.5 mg/day or 1 mg/day), initiated in 2007. Overall, the mean time to HBsAg clearance was 9.4 +/- 4.5 months. Seroconversion occurred in all patients, after a mean time of 8.0 +/- 3.7 months. In HBeAg negative patients, mean time to HBsAg clearance and to seroconversion were 9.2 +/- 5.9 and 6.8 +/- 4.0 months, respectively. In HBeAg positive patients, mean time to HBsAg clearance and to seroconversion were 9.7 +/- 0.6 months and 10.0 +/- 2.6 months, respectively. In this case series, seroconversion was maintained and was observed both in HBeAg positive patients and in HBeAg negative patients. Therefore, it may be preliminarily suggested that treatment with entecavir could be associated to HBsAg seroconversion in a short period of time, in both HBeAg positive and HBeAg negative HBV patients.