VHE Spectral properties of MRK 501 as seen by the CAT telescope in 1997

We report here on observations of Mrk 501 at energies > 250{GeV} carried out between March and October 1997 with the CAT Telescope. This BL Lac Object was in a very high state of activity during 1997, both in VHE gamma-rays and hard X-rays. CAT data show a curved spectrum and a correlation between the gamma-ray intensity and spectral hardness. These VHE spectral properties of Mrk 501 and the correlations with the simultaneous BeppoSAX X-ray data shed light on the possible underlying emission mecanisms. The consequences for new blazar unification schemes are examined.