Combination of CDF and D0 Results on the Mass of the Top Quark
  We summarize the top-quark mass measurements from the CDF and DO experiments at Fermilab. We combine published Run-I (1992-1996) measurements with the most recent preliminary Run-II (2001-present) measurements using up to 1 fb-1 of data. Taking correlated uncertainties properly into account the resulting preliminary world average mass of the top quark is Mtop = 171.4 +/- 1.2 (stat) +/- 1.8 (syst) GeV/c2, which corresponds to a total uncertainty of 2.1 GeV/c2. The top-quark mass is now known with a precision of 1.2%. 
Tevatron Electroweak Working Group (for the CDF Collaboration, D0   Collaboration)