A new and effective method for developing ultralow-loss glasses for long-distance optical fiber systems is presented. The idea is based on the observed strong effect of a very small amount of alkaline or alkaline-earth impurities on structural relaxation of “frozen-in” density fluctuations. Efficiency of this method is demonstrated in the case of silica glass withNa2Oof less than 50 wt. ppm, where the light scattering loss was reduced by 13&percent; by the addition of only10 wt. ppm (≈1×10−3 mol &percent;) Na2O.Various problems in developing ultralow-loss fiber materials in multicomponent glasses are avoidable in this method, since concentrations of dopants are very small. ©1997 American Institute of Physics.