The surface self-diffusion coefficient of poly-crystalline silver has been measured as a function of temperature in the range from 200°C to 600°C by the radioactive tracer and lathe-sectioning technique. It has been found that the surface self-diffusion coefficient in the range from 200°C to 500°C can be expressed as follows: D_s = 4.5 ×10^-2 exp( -11,700/RT) cm2/sec. The values of activation energy and frequency factor are in fairly good agreement with the result of Nickerson and Parker. It has been also found that Fisher’s model of the surface diffusion can be successfully applied in the present work. Considering the value of activation energy, it is suggested that diffusants are in a state of adsorption.