So, i'm learning mahjong at the moment and there is something I don't understand. When you expose a set, do you need to discard a tile afterwards? Also, do you draw before you expose a set?

If been trying to understand the game but the many different versions and rules makes it very hard to find definitive rule explainations.

  • "Many different versions and rules" means there really isn't a single definitive answer - there's different answers that are each definitive for specific rule sets
    – Andrew
    Dec 29, 2021 at 15:27

1 Answer 1


By "exposing a set", I assume you mean the move when you take a just-discarded tile to complete a set you have in hand. When that happens:

  1. You declare the match ("pong" if you're completing a 3-of-a-kind, "chow" if you're completing a run).
  2. You reveal the matching tiles from your hand.
  3. You take the tile the other player discarded and add it to your set.
  4. If you achieved mahjong (four sets and a pair1), you may declare it and the hand ends. If not, or you don't want to declare it, you discard a tile and play continues to your right (so if the discard wasn't from the player to your left, it changes the play order).

You don't draw a new tile, because the tile you took counts as your draw - you should always have 13 tiles in hand, or 14 when it's your turn, not counting any bonus tiles. You can only call chow from the player to your left2 , i.e. the one you'd be playing after anyway, but you can call pong from any other player's discard.

If you're completing a 4-of-a-kind ("kong"), then it is slightly different. You reveal your 3 matching tiles, take the discarded tile, then you draw a tile from the back end of the wall and discard a tile. The fourth tile in a kong essentially becomes a bonus tile that doesn't count towards your 13 tiles in hand, so you have to replace it so that you can still have a complete hand.

  1. In general, a mahjong hand is four sets and a pair. Different variants also have different "special hands" with special combinations that also achieve mahjong. These are quite rare.

  2. At least in some variants, if you need the chow to immediately complete and declare a mahjong, you can claim it from any player's discard.

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