  We have investigated the Tully-Fisher relation for Polar Ring Galaxies
(PRGs), based on near infrared, optical and HI data available for a sample of
these peculiar objects. Many PRGs show larger HI line-widths than expected for
the observed K band luminosity, and this result is confirmed by a larger sample
of objects, based on B-band data. This observational evidence may be related to
the dark halo shape and orientation in these systems: the larger rotation
velocities observed in PRGs can be explained by a flattened polar halo, aligned
with the polar ring.
