  The observational evidence for the existence of a non-zero cosmological
constant is getting stronger. It is therefore timely to address the question of
its eventual effect on the dynamics of galaxies, clusters and larger structures
in the Universe. We find, contrary to a recent claim, that the influence of the
cosmological constant has to be negligible for, e.g., the rotation curves of
galaxies. On larger scales, starting with large galaxy clusters, there are
potentially measurable effects from the repulsive addition to the Newtonian
gravitational force caused by the cosmological constant.
