  We present the first results of a study aimed to detect large HI structures
in radio galaxies. In two of the three cases presented (Coma A and B2 0648+27),
the detection of a large amount of HI distributed over several tens of kpc
suggests a major merger as origin of the observed system and allows to infer
when this merger must have occurred. The situation is less clear for the third
object (3C 433). We propose an evolutionary sequence for one of the radio
galaxies studied. The implications of this study of neutral hydrogen in nearby
radio galaxies for high-z objects and ``normal'' (i.e. radio-quiet) elliptical
galaxies are also discussed.
