  The cluster environment is the site of important transformations in galaxies
at a relatively recent cosmological epoch: the galactic morphological types and
star formation activity have evolved significantly during the last few Gyrs.
How is this related to the galactic gas content? The first part of this paper
briefly presents the optical observations of galaxies in distant clusters,
while the second part focuses on the link between the HI content and the star
formation activity, presenting the results of a multiwavelength study of the
cluster A2670 (z=0.08) where 42 galaxies have been detected in HI. We show the
star formation properties of the HI-normal and HI-deficient galaxies and
discuss their dependence on the location within the cluster. Finally, we
compare A2670 with clusters at intermediate redshift and with the Coma cluster.
