Giuricin, GiulianoMardirossian, FabioMezzetti, MarinoPersic, MassimoSalucci, Paolo2012-08-022012-08-021993-08-11https://openscience.sissa.it/handle/1963/60879 pages (2 figures not included, available upon request), LATEX, SISSA Ref. 132/93/AWe present an observational mass function ranging from galaxies to massive galaxy clusters, derived from direct dynamical mass estimates. Our mass function shows, in the low-mass range of galaxies and groups, a behaviour in agreement with that of standard CDM (n=-2), while in the high-mass range (clusters) our mass function is shallower (and thus contains more power) than standard CDM; it also results shallower than the recent mass function by Bahcall & Cen (1993, ApJ 407, L49).enPreprint