  Because of its proximity and richness on late-type galaxies, the Virgo
cluster has been the subject of numerous studies exploring the effect of the
intracluster environment on galaxy evolution. First discovered nearly three
decades ago by Davies & Lewis (1973), the neutral hydrogen (HI) deficiency of
the Virgo galaxies is now a well-established observational phenomenon also
observed on many other rich clusters. A number of studies on the neutral
hydrogen 21-cm line of Virgo cluster galaxies --from the lenticular and largest
spiral types through the faintest dwarf irregulars-- show that a significant
number of these objects have lost a substantial fraction of their atomic
hydrogen and are HI-deficient when compared with galaxies of the same optical
properties in less dense environments.
