  We present the results of the observations of the giant bursts from the X-ray
pu lsar A0535+26 made by HEXE onboard Mir-Kvant in April 1989, November 1993
and February 1994. The pulse periods were measured, pulse profiles in different
energy bands were produced, and their variability was investigated.
  The power density spectra (PDS) in 2x10^(-3)-1 Hz range is presented, which
shape is typical for flicker-noise processes, usually observed in black hole
candidates. The noise rms grows with energy from ~20% at 20 keV to ~30% at 80
keV. The source photon spectrum in the 15-200 keV energy range and its
variability over the pulse phase are reported. Approximately the shape of the
spectrum can be described by the "canonical" model for X-ray pulsars with
power-law index g~1.1, cut-off energy E_c~23 keV and folding energy E_f~19 keV.
All these parameters are weakly dependent on the luminosity. The most
significant deviation from this continuum is observed at ~100 keV in the
spectrum of the main pulse maximum. This feature is interpreted as a cyclotron
line. Comparison of the HEXE data with the data from BATSE/CGRO (Bildsten et
al., 1997) shows that in the high luminosity state (L~10^38 erg/s) the pulsar's
pulse profile differs substantially from the pulse profile in the
low-luminosity (L~5x10^36 erg/s) state. This difference is explained by the
qualitative change of the polar cap structure with formation of the accretion
columns.
