This paper reports the first successful measurement of the specific surface-area of a lithium metal anode by employing the BET method under optimum experimental conditions. The test cell used here is an M-size cylindrical cell with a lithium anode and an amorphous-V2O5-P2O5 cathode. The experimental results clearly reveal that the lithium surface-area increases after a low-rate discharge cycle. For example, the specific surface area of a lithium at a low-rate discharge current density of 0.2 mA cm(-2) is 26 m(2) g(-1) which is twice that at a high-rate discharge current of 3 mA cm(-2). The influence of the discharge depth on the lithium surface-area is also examined. The surface-area measurement method described here will be useful in terms of finding a way to improve both the cycle life and safety of rechargeable, lithium-metal cells.