We report on measurements of the mass and total decay width of the W boson
with the L3 detector at LEP. W-pair events produced in e(+)e(-) interaction
s between 161 GeV and 183 GeV centre-of-mass energy are selected in a data
sample corresponding to a total luminosity of 76.7 pb(-1). Combining all fi
nal states in W-pair production, the mass and total decay width of the W bo
son are determined to be m(W) = 80.61 +/- 0.15 GeV and Gamma(W) = 1.97 +/-
0.38 GeV, respectively. (C) 1999 Elsevier Science B.V. All rights reserved.