Henry Kissinger disclosed to the world last night that he likes opera but can't stand Wagner.

"I have this friend in Vienna who describes a Wagner opera this way. You go to the opera at 6:30 and you sit there all evening and finally you look down at your watch and it's only 6:45," he related to a gathering of potential corporate donors to the Washington Opera during a party at the Watergate.

This flagrant example of esthetic bias emerged during a speech introducing the company's general director, Martin Feinstein, and the president of its board, David Lloyd Kreeger, whom Kissinger referred to as "these men at my side with their utterly mercenary motives." Kissinger is chairman of what the company calls its "Challenge to Greatness" campaign.

Fortunately for them, the Opera didn't perform any Wagner in the 10 1/2-week season that ended just last weekend. Kissinger didn't exactly ban Wagner, but he said, "I told them I couldn't chair the fund-raising drive in a year when they had a Wagner opera. There's nothing political about it. It just bores me." Those who dared to disagree remained discreetly quiet.

The former secretary of state was in particularly vigorous verbal fettle. He drew many laughs when he referred to Feinstein, who himself has more than a touch of what might delicately be called Kissingerian "forcefulness," as "the kind of monomaniac under whom this kind of improbable thing can succeed." Feinstein drew more laughs as he retorted that two years ago "when the board asked me to become the director, I told them that I thought I had enough ego to do the job."

These exchanges were the prelude to getting the message to a wide spectrum of the denizens of corporate Washington that 1) the recent season was the most successful ever, and 2) it was the most expensive ever.

Opera is the most expensive art form. Normally an opera company expects to pay for about a third of its costs from the box office and the rest must come from contributions. As Kreeger, who is the former chairman and chief executive officer of GEICO, explained to the group, "That means that every time anybody buys a $20 seat some corporation must put up $40 for that seat."

This year the Washington Opera did a little bit better than that, bringing in $1.36 million from ticket sales, which is 36 percent of the budget. That was one benefit of a 47 percent rise in ticket prices. Also, said Kreeger, "We ran over our budget by about $500,000."

This season was a major turning point in the growth of the 26-year-old company. For the first time it presented a full-scale repertory season. Seven productions, including five new ones, rotated in the last two months, and to pay for it the fund-raisers must come up with about $2.5 million.

Kreeger was quite direct about it. "In the old days we would ask for a minimum contribution of from $500 to $1,000. Now that we are aspiring to world status, we must look to a minimum contribution of $5,000. We don't think it is too greedy to ask for that much." Kissinger was standing right next to him, and neither he nor any of their guests pulled out their wallets.

When Feinstein thanked Kissinger for inviting so many of his friends, Kissinger deadpanned, "I can't tell you how much it means to me to be told I have this many friends." There were about 100 persons there, among them Paul Dragoumis of PEPCO (he is the treasurer of the Opera board), AFL-CIO head Lane Kirkland, Clark MacGregor of United Technologies, chairman of the board of The Washington Post Co. Katharine Graham, David Brinkley, the Watergate's Nicholas Salgo (the Watergate contributed the party), Woodward & Lothrop chairman Edwin Hoffman, Mobil Oil's Paul Petrus and former World Bank president Robert McNamara.