It is shown that the erosion of the first wall due to sputtering in a tandem mirror fusion reactor (TMR) is not a serious problem. An erosion rate in the 0.3 μm/yr to 0.3 mm/yr range for the Mirror Advanced Reactor Study parameters is estimated. The natural end loss in a TMR deposits most of the charged-particle power and fueling current on the end collectors, far from the first wall. Therefore, most of the heating and sputtering take place on massive structures in the end tanks and do not affect the design of the first wall and blanket. Furthermore, the cool halo plasma in a TMR protects the first wall by reducing both the energy and the flux of particles that recycle between the wall the plasma.