A revoke (also called a renege) is a violation of important rules regarding the play of tricks in trick-taking card games serious enough to render the round invalid. A revoke is a violation ranked in seriousness somewhat below overt cheating, with the status of a more minor offense only because, when it happens, it is usually accidental.

Trick-taking games normally have several rules regarding which cards may and may not be played to a trick. For example, most games require a player to follow suit or play in the suit led, if possible. Rules of this sort are sometimes called "honor rules", because there is no way to detect a violation at the moment of its commission. However, the irregularity will normally be discovered later, and there are usually strict penalties for revokes.

Some "honor rules" in different trick-taking games

• Spades and Euchre require that players play to the suit led, unless void in it.
• Hearts requires that players follow the suit led. In some variants, a player holding the Queen of Spades and void in the led suit is required to play it.
• Pinochle requires players to
  • play to the led suit unless void in it, with a potentially winning (higher than the highest-so-far) card if possible;
  • if void in the led suit, trump with a potentially winning card;
  • if unable to do any of those things, play anything.
• Bourré requires players to
  • play to the led suit unless void in it, with a potentially winning (higher than the highest-so-far) card if possible;
  • if void in the led suit, trump with a potentially winning card;
  • play to bourré as many other players as possible.

Penalties for revokes vary:

• In Bridge the penalty for a revoke is normally one or two tricks scored against the offending partnership, depending on the exact circumstances, but if the non-offending side is more seriously damaged than that (typically because the revoke made a critical entry worthless), then they are compensated accordingly.
• In Pinochle and many other bidding trick games, a revoke results in an automatic set, or failure at the bid, normally precipitating a penalty.
• In Hearts a revoking player receives 26 penalty points (all of them) and other players receive none.
• In Bourré a revoking player must forfeit an amount of money equal to the pot.

Normally revokes are given a penalty equal to the most severely negative outcome of the round possible. The intention is to discourage the practice, which upsets other players' strategies to the point where the only acceptable resolution may be to declare the round void.

Therefore, a revoke rarely has a strategic advantage, except in king-maker scenarios.

Since hands are (usually) concealed, a player can revoke (accidentally or intentionally) without being caught immediately. For example, if a player does not play a spade to a trick where spades were led, other players will simply assume that player has no spades and note the fact in future play decisions. However, most trick-taking games play a hand until exhaustion, and attentive players will soon notice the violation when a spade is played to a subsequent trick.