  We investigate the rare baryonic ${\Lambda}_b\rightarrow{\Lambda}l^+ l^-$
decays in a non-universal $Z'$ model, which is one of the well-motivated
extensions of the standard model (SM). Considering the effects of $Z'$-mediated
flavour-changing neutral currents (FCNCs) we analyse the differential decay
rate, forward-backward asymmetries and lepton polarisation asymmetries for the
${\Lambda}_b\rightarrow{\Lambda}l^+ l^-$ decays. We find significant deviations
from their SM predictions, which could indicate new physics arising from the
$Z'$ gauge boson.
