  The measurement of the beauty quark production cross section in deep
inelastic scattering with the ZEUS detector at HERA is presented. The cross
section for beauty quarks, measured in the kinematic range $Q^2 > 2$ GeV$^2$
and $0.05 < y < 0.7$, and for events with at least one muon and one jet in the
Breit frame, is somewhat above the next-to-leading order (NLO) QCD prediction,
but in agreement within the experimental and theoretical uncertainties.
