Part I: Games & Gaming · Wheel Games — Roulette

En Prison

Roulette

A player-favorable rule applied to even-money outside bets (red/black, even/odd, high/low) in some European and French roulette games. When the ball lands on zero, instead of losing the entire wager, the player’s bet is held “in prison” (locked or impounded) for the next spin. If the player’s original bet wins on the subsequent spin, the full wager is returned with no additional winnings; if it loses, the wager is forfeited. Some casinos offer a variation where the player can choose to recover half the bet immediately rather than leave it en prison. The en prison rule reduces the house edge on even-money bets from 2.70% to approximately 1.35%, making it one of the most favorable rules for players in any casino game.

In practice

En prison is standard in French roulette and is sometimes available in European roulette, particularly in premium markets. It is virtually never offered on American double-zero wheels. Macau VIP rooms occasionally offer en prison or la partage on request for high-limit players.

One entry from the Casino Industry Glossary — 1,157 terms written for surveillance, compliance and operations professionals rather than for players. Definitions describe industry usage; where a term carries a regulatory meaning, verify against the instrument that governs your jurisdiction.