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The IESP experiment implemented onboard the Interball auroral probe measures the six components (3<i>B</i>, 3<i>E</i>) of the waves in the ULF range: 0.1–10 Hz and from time to time 0–30 Hz. Two different kinds of waves have been observed in the auroral region at altitudes between 10 000 and 20 000 km: (1) electrostatic emissions which consist of quasi-monochromatic structures with frequencies above the oxygen gyrofrequency, superimposed on a wide band signal interpreted as a Doppler broadening, (2) electromagnetic wide band spectrum fluctuations. These emissions are interpreted as current-driven electromagnetic or electrostatic ion cyclotron waves. The electromagnetic/electrostatic character is controlled by the plasma parameter <i>&#x03B2;_i</i> and by the O⁺ concentration.<br><br><b>Key words. </b>Magnetospheric physics · Auroral phenomena · Plasma waves and instabilities · Interball Auroral probe</p>