By Barbara Seagram 
Courtesy of BarbaraSeagram.com
If I ask a student how he plans to make a hand, the first answer I always get is “I’m going to crossruff.” There is something joyous about a crossruff that excites the average bridge player! Contrary to popular opinion, however, the true crossruff occurs relatively seldom.
It is just a fact… (memorize this fact!) that ruffing in your hand rarely gets you extra tricks. Ruffing in dummy always gets you extra tricks.
The following is a deal on which you must not crossruff.
In a true crossruff, you do not draw trumps. You need to have them both in dummy and in your hand. Therefore, if you own a long good side suit (non-trumps) you must not use the crossruff technique.
Check out this hand where South is in ♠! Yikes! Only 28 HCP between the two hands.
West leads the ♥K, and South has three club losers. If he crossruffs this hand, she will lose the ability to pull trumps and then she will be unable to “enjoy” playing the diamond suit as opponents will then ruff the diamonds.
South must ruff all his clubs in dummy, returning to his hand once with the ♦Q and once more by ruffing one heart only in the declarer’s hand… we will ruff the heart just for purposes of communication with South hand. He must be careful to ruff the third club with dummy’s ♠A so that he will still have a smaller spade to get back to hand and pull the trumps. After trumps are all gone, declarer can now play diamonds and claim, “The rest are mine.”
On this next deal, North-South bid a lot and got to 5♦. South is declarer.
South has four club losers and two potential heart losers. Four losers too many. And no long strong other non-trump suit.
Hurrah! Enter the crossruff. You will really be ruffing clubs in dummy, thereby gaining extra tricks, but you will need a way to get back to declarer’s hand. The only way will be by ruffing spades from dummy in declarer’s hand. Do not pull any trumps at all. You will need to ruff all four clubs from South hand with dummy’s trumps.
This is a perfect, classic crossruff hand. These come up rarely.
One more example… with an important adjunct.
South is in 6♠. He has one heart loser and four club losers. Those clubs cannot win tricks without performing magic on them, so call them losers.
Once again, the perfect cross ruff hand. You win the ♦A, and now what?
If you embark on your cross-ruff now, then while you are ruffing your losing xlubs in the dummy, West will pitch one or two hearts. Now, since you have not pulled trumps, when you go to play the ♥A and ♥K, West will be able to ruff them.
MORAL OF STORY: When you are cross-ruffing and have top cards in a side suit (hearts), you must first cash those side-suit winners before commencing the cross-ruff or they will be ruffed by your opponents later.