Thebb¯production cross section has been measured in collisions of 920 GeV protons off a nuclei target using the HERA‐Bdetector. The identification ofbb¯events was done via inclusive bottom quark decays intoJ/&psgr; by exploiting the longitudinal separation of theJ/&psgr; →l+l−decay vertices from the primary proton nucleus interaction, where both the &mgr;+&mgr;−and thee+e−decay channels have been reconstructed. The first measurement, using data collected during a short period in 2000, yields a cross section in the combined analysis of&sgr;(bb¯) = 32−12+14(stat)−7+6(sys)nb/nucleon. On the most recent data samples taken in 2002/03, a much more accurate measurement with the uncertainties reduced to 10&percent; is expected. © 2004 American Institute of Physics