  Using the data collected with the DZero detector at sqrt(s)=1.96-TeV, for
integrated luminosities of about 180 pb^{-1}, we have measured the ratio of
inclusive cross sections for p+pbar->Z+bjet to p+pbar->Z+jet production. The
inclusive Z+b-jet reaction is an important background to searches for the Higgs
boson in associated ZH production at the Fermilab Tevatron collider. Our
measurement is the first of its kind, and relies on the Z->e^+e^- and
Z->mu^+mu^- modes. The combined measurement of the ratio yields 0.023 +/- 0.005
for hadronic jets with transverse momenta p_T>20 GeV/c and pseudorapidities
|eta|<2.5, consistent with next-to-leading order predictions of the standard
model.
