The mode conversion of ordinary polarized electromagnetic waves into electrostatic cyclotron waves in the inhomogeneous ionospheric plasma is investigated. Near resonance the warm plasma dispersion relation is a function of the angle &thgr; between the geomagnetic field and the density gradient and of the wave frequency &ohgr;, where &OHgr;≤&ohgr;≤2&OHgr; and &OHgr; is the electron cyclotron frequency. The differential equations describing the electric field amplitudes near the plasma resonance are studied, including damping at the second gyroharmonic. For certain values of &ohgr; and &thgr; (e.g., &thgr;<45¿, &ohgr;~2&OHgr;) the wave equations reduce to the parabolic cylinder equation. The energy transmission coefficients and power absorbed by the cyclotron waves are calculated. The vertical penetration of the plasma wave amplitudes is estimated using a WKB analysis of the wave equation. ¿American Geophysical Union 1991