Cyclotron resonance is observed in a semiconducting n-InAs-GaSb superlattice by measuring the change of the far-infrared-radiation (FIR) transmission in a magnetic field at three different FIR frequencies. The angular dependence of the cyclotron resonance position is measured and shows a two-dimensional behavior. The resonance observed is attributed to an upwards shift of 145 meV of the InAs conduction band as a consequence of the superlattice subband formation. A simple calculation leads to a value of 195 meV for this shift. © 1982 The American Physical Society.