Defending against a wrist grab. In this case a same side wrist grab (right to left or left to right).

1. A same side wrist release is when someone grabs your arm directly across from you. In other words, their right hand grabs your left wrist. The first thing you should do is to close your fist. This prevents them from grabbing your fingers and bending them back putting you in a worse situation.
2. In the next step you are going to step back with the opposite leg to allow you to get your whole body into the release. As you prepare to do this you want to turn you wrist so that the inside bone (radius) faces the opening between his thumb and forefinger.
3. Stepping back (with the opposite foot) allows your full body power to assist in the release. Pull your fist all the way back to your opposite shoulder. This entire process should be done in one smooth step. Keep your eye contact on your attacker. If this is a nuisance attack, all that may be necessary from here is to step back and tell your attacker to “back off”.
4. However if this is a more serious situation, a good follow up response is with a back fist strike to the temple, nose or face.

If necessary, and the situation dictates, use additional follow up techniques until you feel it is safe.

This clip is taken from Street Self Defense 101. Please visit http://www.easy-self-defense.com for more details.