  We present a comprehensive study of event-by-event multiplicity fluctuations
in nucleon-nucleon and nucleus-nucleus interactions from AGS/FAIR to RHIC
energies within the UrQMD transport approach. The scaled variances of negative,
positive, and all charged hadrons are analysed. The scaled variance in central
Pb+Pb collisions increases with energy and behaves similar to inelastic p+p
interactions. We find a non-trivial dependence of multiplicity fluctuations on
the rapidity and transverse momentum interval used for the analysis and on the
centrality selection procedure. Quantitative predictions for the NA49
experiment are given, taking into account the acceptance of the detector and
the selection procedure of central events.
