A crossruff is a play in contract bridge, in a suit contract, where the tricks are made by taking alternate ruffs in each hand. It is used mainly by the declaring side, but can be used by the defenders in some situations.

In order to use a crossruff, each player in the partnership must have shortness in a non-trump suit, accompanied with appropriate length in the opposite hand. Also, each partner must be short in the suit that his partner is long in. It is preferable that both players have an equal number of cards in the trump suit, otherwise a regular ruff is usually more effective, as it has the added benefit of establishing the trump suit.

The mechanics of the crossruff are simple. This is an extreme example of crossruff:

♠	AJ8543	W         E	♠	Q109762
♥	-		♥	-
♦	-		♦	9876543
♣	9876543		♣	-

West plays the grand slam of 7♠ despite having only 7 high card points. The declarer can draw the outstanding trump king, ruff the diamonds in dummy, going back to the hand by club ruffs. Unless both minor suits are divided 6-0, one of the minor suits will ultimately become high and provide the missing two tricks. In summary, the declarer took one trick by leading a high card (the ace of trumps) and 10 tricks by cross-ruffing; the remaining two tricks came as result of long suit establishment.
 

However, there are several risks involved with crossruffing. First of all, when the opponents run out of cards in the suit(s) lead by declarer, they can overruff, that is, play a higher trump card than the declarer's. Also, this play leaves the trump suit unestablished, so the defenders can possibly steal back a trick or two because the declarer used the trumps for ruffing rather than drawing out the opponents' trumps. Therefore, this play is only suggested when other means of gaining tricks, such as establishing the trump suit or traditional ruffing, would fall short. However, this play is preferred over a finesse, especially if only one or two extra tricks are needed, as the risks are rather low unless you take several tricks using this method.

It is often important to cash side-suit winners before commencing a cross-ruff, otherwise the opponents may discard in the side-suit, allowing them to trump the winner later.

In some cases, it is effective to cross-ruff after drawing the opponents trumps, when this can be done with trumps remaining in both hands. In other cases, it is effective to cross-ruff only until one opponent becomes likely to be void in a particular suit, and revert to drawing trumps thereafter.

The basic defense against crossruff is simple: lead trumps whenever possible, removing trumps from both declarer's hands. Often, the defense must lead trumps from the very opening lead in order to prevail. Thus, it is important to recognize the situations when a trump opening lead is called for ? usually, they arise when both declarer and dummy have bid other suits but found the trump fit in the third one.