Abstract We theoretically examine the behaviour of Cherenkov radiation in a lossy, dispersive and resonant medium when emission is assisted by an external electromagnetic field. Under the appropriate coherence conditions for Cherenkov emission, we anticipate a large increase of the emission yield at resonance. Our predictions are implemented by numerical estimates for cuprous oxide (Cu20 ). Pacs: 61.43.Fs, 77.22.Ch, 75.50.Lk