The DENIS $IJK$ survey of the entire southern sky is beginning observations this year. It will return one million images, representing 4 Terabytes, among which nearly $10^8$ stars and up to one million galaxies. The main extragalactic applications of such a multi-band, digital, near-IR 2D survey are listed, and the importance and feasibility of a spectroscopic followup are discussed. First estimates of the capabilities for galaxy extraction are given, and illustrated with preliminary images of three very bright galaxies. Contributed talk at ESO/MPA workshop (June 95) on "Spiral Galaxies in the Near-IR", ed. D. Minniti (Berlin: Springer Verlag) self-unpacking (uuencoded gzipped PostScript)