  We report on recent result according to which the fermion-fermion interaction
mediated by axions and axion-like particles can be revealed by means of neutron
interferometry. We assume that the initial neutron beam is split in two beams
which are affected by differently oriented magnetic fields, in order that the
phase difference depends only by the axion-induced interaction. In this way,
the phase difference is directly related to the presence of axions.
