We studied the timing of withdrawal of lamivudine administration for HBe Ag-negative chronic patients. The amount of serum HBV DNA was measured using the Amplicor HBV monitor (AM) and the Real-time Detection direct (RTD-direct). All values became less than 2.6 log copies/ml according to the AM method after administration. Five of 16 patients were found to have no HBV according to the RTD-direct (less than 1.0 log copies/ml). Thus, withdrawal of administration was attempted for these five patients. After the withdrawal, the viral load and ALT levels had increased in all patients. These results showed the difficulty of withdrawing lamivudine administration from HBe Ag-negative chronic patients, even though they have very low viral load in serum by the treatment.