An absolute value for the isotopic abundance ratio of natural silver was obtained by the use of isotopic standards prepared from nearly pure separated silver isotopes. Mass spectrometric data resulted in a value for the ratio (Ag/ sup 107//Ag/sup 109/ = l.0754/sub 7/ plus or minus 0.0013). Within the sta ted limits, no variation in natural abundance was found among six samples of native silver and commercial silver nitrate. A seventh native silver sample, obtained from Cobalt, Ontario, showed a statistically significant deviation. The calculated physical and chemical atomic weights of silver are respectively. On the recently proposed unified physcial and chemical atomic weight scale (C/sup 12/ = 12), the atomic weight is 107.8685 plus or minus 0.0013. The indicated uncertainties are overall limits of error based on 95% coafidence limits for the mean and on allowances for effects of known sources of possible systematic error. (auth)