  The available data on large scale structures seem to favour models with mixed
dark matter (MDM), i.e. with a hot and cold component in a rather well--defined
amount, or with some form of ``warm" dark matter. I discuss some prospects for
these new scenarios for DM in the context of supersymmetric extensions of the
electroweak standard model. In particular, I emphasize the intriguing link
which exists between the present prospects of solution of the DM puzzle and the
explicit or spontaneous breaking of baryon and/or lepton number symmetries.
Some consequences on the issue of baryogenesis are worked out.
