  Research on the core of medium and high z clusters of galaxies can derive
great benefits from integral field spectroscopy, and a key role in this respect
will be played by the Integral Field Unit (IFU) being developed by the VIRMOS
Consortium as part of the VIMOS spectrograph. After a brief technical outline
of the instrument, some of the problems to be addressed by data reduction
techniques are described, and the scientific issues to which VIMOS IFU is
likely to give its major contribution are pointed out.
