  The polarisation properties of the intrinsically small (< 20 kpc) radio
sources are briefly discussed. At centimetric and decimetric wavelengths,
substantial polarised emission is often detected in quasars and, at a lower
level, in radio sources identified with galaxies with projected linear sizes in
excess of a few kpc. The projected linear size at which some polarised emission
is detected decreases with observing frequency.
  High Rotation Measures are commonly found in these sources, implying high
electron/ion densities and/or strong interstellar magnetic fields. For the
objects found unpolarized at resolutions of the order of a few pc, either the
source magnetic field is highly disordered or the scale of ambient magnetic
field cells is not resolved.
