AbstractHigh excitation luminescence spectra from a homogeneous electron–hole system are investigated in undoped unstrained InxGa1−xAs/InP quantum wells in magnetic fields up to 12 T. Clear excitonic effects are observed in the optical spectra of neutral, dense magnetoplasmas at low temperatures. These appear as the suppression of the density dependence of transition energies between the uppermost occupied (Je = jh = N) Landau levels in the range of filling factors N < v/2 < N + 1. The effect disappears with increasing temperature. The experimental results are in agreement with theoretical calculations including both the inter‐Landau‐level coupling and screening effects. In a magnetoplasma with an integer filling factor, Landau‐level transitions near the Fermi level are well described in terms of excitons and deexcitons.