By means of Na-22 radioactive tracers the Na+ tracer diffusion coefficient in the glass Na2O.2SiO2 has been determined in the temperature range of 300 to 400-degrees-C. The same sample batch has also been studied by quasielastic neutron scattering using pulsed neutrons of 19.8 angstrom wavelength. From the observed linebroadening at 420-degrees-C we derive a Na+ self-diffusion coefficient of 3.1 x 10(-8) cm2/s, in excellent agreement with the radioactive tracer results.