  The study of neutral hydrogen emission and absorption in radio galaxies is
giving new and important insights on a variety of phenomena observed in these
objects. Such observations are helping to understand the origin of the host
galaxy, the effects of the interaction between the radio jet and the ISM, the
presence of fast gaseous outflows as well as jet-induced star formation. Recent
results obtained on these phenomena are summarized in this review. Although the
HI observations concentrate on nearby radio galaxies, the results also have
relevance for the high-z objects as all these phenomena are important, and
likely even more common, in high-redshift radio sources.
