  We review previous work on neutrino mass textures in gauge theories. Such
textures may arise as a result of flavour symmetries. In a given theory, it is
possible to give a classification of heavy Majorana neutrino mass matrices,
assuming the Dirac masses of the neutrinos to be of the same form as the ones
of the up-quarks. Heavy Majorana neutrino mass matrices leading to large
neutrino mixing, are tabulated as an example. Such solutions are now of
interest, in the light of the Super-Kamiokande data.
