  We briefly review the properties and physical consequences of quasiperiodic
oscillations (QPOs) seen on many occasions in the X-ray emission from
black-hole binary systems. We also report on the discovery of QPOs at 164 and
328 Hz in GRS1915+105. These appear to be analogous to the harmonic systems of
high-frequency QPOs seen in XTEJ1550-564 and GROJ1655-40.
