Top-quark mass predictions from W,Z masses and Z partial widths.

We use recent measurements of the {ital W}- and {ital Z}-boson masses and the leptonic, hadronic, and total {ital Z} widths to constrain the top-quark mass in the standard model, including full radiative corrections. From a maximum-likelihood analysis we find the most likely value of {ital m}{sub {ital t}} to be 151 GeV and we obtain the bound {ital m}{sub {ital t}}{le}200 GeV at 95% C.L. based on the central measured value of the {ital Z} mass assuming a Higgs-boson mass of 100 GeV and {alpha}{sub {ital s}}({ital M}{sub {ital Z}}{sup 2})=0.12.