The viscosity of pre-annealed lead-silicate glass was studied below the glass transition temperature using the fiber-bending method. The viscosities were determined under conditions of loading and unloading. The delayed elasticity and its effect on the viscosity were also investigated. In the case of equal loading and unloading times, the viscosity was the same for the loading and unloading processes and the delayed elasticity was larger within shorter periods and smaller for longer ones. In addition, the time necessary for the recovery of the delayed elasticity increases with increasing loading time.