Electron impact ionization of gas phase silver clusters Ag(n), n less-than-or-equal-to 36 has been achieved in the threshold region. The vertical ionization potentials in this region clearly demonstrate the evidence of shell effects as well as a distinct even-odd oscillation up to n congruent-to 20. Their general size dependence is somewhat different from that of the alkali metal clusters due to the presence of the d-electrons.