Someone asked about this on a discussion forum so I figured I would write a little bit about this. There is sometimes a special rule that players will be allowed to take advantage of. This rule applies to both American and European roulette in some casinos. Note that not all casinos will allow players to use this and you will usually notice the En Prison rule at big casinos in Las Vegas and Atlantic City, especially if you are playing on a single zero wheel.

Ok, basically if you are betting on red or black, and the ball lands on a green slot, the dealer will give you the option to use the En Prison rule. Now this only applies when you are betting on black or red, and then the ball lands on the single zero or double zero (if your roulette wheel has the 00 slot).

For example, if you bet $100 on black and the wheel lands on a zero, the first option is to surrender half of your bet or lose $50. The other option is to chose to go into prison “En Prison”. If you choose to go in prison, the dealer will place an “En Prison” marker over your bet and you leave your $100 on the table and the dealer spins the wheel once more.

The goal is to not have the ball land on the green zeros or the red slots since your original bet was black. If the ball lands on single or double zero again, you lose the bet. You will also lose the bet if the ball lands on red. If it does not land on any zeros and it lands on black, then you go out of prison and you break even. When using the En Prison rule, you can never win. Basically you lose your entire bet or your break even.