On 2002 we started an observational campaign devoted to the study of the surface composition of Jupiter Trojans. In particular we focused on the study of members of dynamical families: we obtained visible spectra of 80 objects belonging to 10 different families and for 24 of them we obtained also near-infrared spectra. All the investigated bodies have featureless spectra: in particular, no signatures of water ice have been found on the spectra of these primordial bodies. L4 and L5 objects seem to have similar spectral behaviours and no evidence of a possible color-dimension trend has been found. Tentative models of the surface composition, based on the Hapke theory, have been obtained.