Standard Model Constraints On

The results reported in this paper are based on data collected during four years of running at LEP, from '90 to '94. A combined set of published and preliminary electroweak results from the four LEP experiments is used to constraint the masses of the top quark and Standard Higgs boson. The fit yelds M Top = 179 \Sigma 9 +17 \Gamma19 GeV (60 ! MH ! 1000 GeV ) in excellent agreement with the recent determination from CDF and D0 at Tevatron. Using also their direct measurement of M Top in the fit we get an upper limit for MHiggs : MHiggs ! 900 GeV at 95% C:L:. XXX th Rencontres de Moriond, QCD and High Energy Hadronic Interactions, Les Arcs,France March 19-26, 1995. 1 Introduction During the last year important progresses have been achieved for both statistical and systematic errors on the electroweak measurements. The statistics was approximately doubled reaching a total amount of data of about ten millions of hadrons and one million of leptons. The calibration of the LEP energy..