O uchi gari (large inner reap) is one of the original 40 throws of Judo as developed by Jigoro Kano. It belongs to the first group, Dai Ikkyo, of the traditional throwing list, Gokyo (no waza), of Kodokan Judo. It is also included in the current 67 Throws of Kodokan Judo. It is classified as a foot technique, Ashi-Waza.
In right o uchi gari, tori reaps uke’s left leg with his right leg from the inside while pulling uke down. In competition, the reaping action of the classical variation is sometimes replaced with a hooking or lifting motion, and the left hand can be used to lift or block uke’s other leg while reaping the other. Control of the opponent should be maintained all the way to the ground.
[From Wikipedia. Original page is here]