We present the preliminary results of a programme aimed at defining a low-resolution near-infrared spectral classification scheme for faint M, L, and T-dwarfs. The method is based on the global shape of R˜100 complete near-infrared spectra from 0.8 to 2.4μm as obtained through a high-throughput prism-based optical element, the Amici device, mounted inside the NICS instrument at the TNG 3.5m telescope (Baffa et al. 2001; Oliva 2000). The aim of our project is to provide an efficient classification scheme based on very low-resolution near infrared spectroscopy, which can be carried on at a 4m-class telescope. The results for the L-type dwarfs have already been presented in Testi et al. (2001), sample spectra for the M and T-dwarfs range are shown in Figure 1. A preliminary application of the method to the classification of young embedded brown-dwarf candidates has been successfully attempted by Testi et al. (2002) and Natta et al. (2002). The method is shown to be accurate and competitive: the high system throughput coupled with the possibility of obtaining in a “single shot” the complete spectrum of the objects make the NICS/TNG system more efficient than existing large telescopes.