Measurement of the b-jet cross section in W+b+X production. The cross section is given for pt(lepton)>20 GeV, |eta(lepton)|<1.1, pt(neutrino)>25 GeV and jets with Et>20 GeV and |eta|<2 for cone size 0.4. The cross section is defined to be proportional to the number of b-jets (and not the number of events). It is also quoted for the W going to a single lepton flavor Result: sigma(W+bjet)xBR(W->lv)=2.74 +/- 0.27 (stat) +/- 0.42 (syst) this result is a factor 3.5 larger than the prediction from Alpgen which was evaluated to be 0.78 pb.