Electron cyclotron radiation has been successfully used in present day tokamaks for plasma heating and current drive. The direction of future tokamak research in these areas is toward higher injected ECRH power levels. Resonant magnetic fields in future devices (5T in ITER), and consequently the resonant frequencies, are only a about a factor of two greater than in existing ECRH experiments (DIII-D, T-10). Studies will be presented that indicate 5–10 MW of ECRH power can be efficiently generated with gyrotron oscillators. We suggest that short pulse experiments are possible in the near term to investigate multi-megawatt gyrotron operation and guide CW gyrotron development.