On February 8, 1992, the Ulysses spacecraft passed through Jupiter's Io plasma torus, where rich spectra of narrow-band resonances were stimulated by the relaxation sounder of the Ulysses unified radio and plasma wave (URAP) instrument. Since the gyrofrequency fg is comparable to the plasma frequency fp in the Io torus, it was predicted that the general classification of stimulated ionospheric Dn resonances, developed for 1≤fp/fg≤8 in the Earth's topside ionosphere, should apply in the Io torus as well as the Earth's magnetosphere (Osherovich, 1989). The URAP plasmagrams (sounder spectra) in the portions of the Io torus satisfying these plasma conditions are dominated by the Dn resonances for frequencies below fp. On most of these plasmagrams the fp resonance is also present, but it is seldom the dominant resonance. Neither upper hybrid nor nfg resonances have been found on these plasmagrams. The identification of Dn resonances has allowed both the electron density and the magnetic field amplitude to be calculated. The derived densities on the outbound pass agree well with a Voyager model of Bagenal (1992). The derived magnetic field values are close to the Goddard Space Flight Center O6 model magnetic field. ¿ American Geophysical Union 1992