This paper reviews the experimental results on lower hybrid current drive in tokamakplasmas. Pulse lengths of 3.5 seconds and currents above 400 kA have been generated atplasma densities such that the wave frequency is greater than about twice the lower hybridfrequency. Current drive ceases above a critical density, nc. However, nc increases withwave frequency. So that for f = 4.6 GHz current drive has been seen at ec ≈1014 cm-3 anda density limit has yet to be established. Evidence for a collisional scaling law forcurrent-drive efficiency is summarized. Detailed measurements of bremsstrahlung X-raysshow a distribution which is qualitatively similar to that predicted by quasilineartheory. Microwave emission at frequencies less than the plasma frequency may shed lighton the current-drive mechanisn. Applications of current drive including plasma andcurrent start-up and transformer recharging are discussed.