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This Letter describes a direct measurement of the W boson total decay width, Γ W, using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of 90 pb-1, collected during the 1994–1995 run of the Fermilab Tevatron pp̅ collider. The width is determined by normalizing predicted signal and background distributions to 49 844 W→ eν candidates and 21 806 W→μν candidates in the transverse-mass region MT < 200 GeV and then fitting the predicted shape to the 438 electron events and 196 muon events in the high-MT region, 100<MT < 200 GeV. The result is G Γ W= 2.04 ± 0.11(stat) ± 0.09(syst) GeV.