Remember those dreaded, three-sided Trilateralists, the international conspirators headed by David Rockefeller who were going to take over the world? Jimmy Carter was one. George Bush used to be one, too, and it cost him dearly in his campaign last year against Ronald Reagan.

Well, guess who's coming to the White House. Guess who invited them. Guess who will head delegation. Right. The Trilateralists are coming. President Reagan has asked them to come. They will be led by David Rockefeller. The Trilateralists have landed, and the conspiracy theorists will no doubt be close behind.

For the record, the Trilateral Commission is a New York-based policy group formed by Rockefeller in 1973 in a reaction to the nationalistic foreign economic policy of President Nixon, which disturbed some traditional U.S. allies. It drew together tycoons from North America, Europe and Japan to discuss the virtues of international cooperation. it published tomes such as "The Reform of International Institutions" and "Seeking a New Accommodation in World Commodity Markets."

And it became firmly fixed in the mythology of both the far right and the far left as the center of a shadow world government headed by Rockefeller which had its conspiratorial tentacles in every western capital and multinational corporation. There were those who credited the Trilateralists with a leading role in removing Nixon from power. There were others who found this same debating society at the heart of a dangerous conspiracy to elect Bush.

A year ago during the New Hampshire primary campaign Bush was badgered repeatedly by questioners who asked why he had been a Trilateralist. When Bush tried to explain at one tumultuous meeting that he would never be part of an organization that advocated world government, he was drowned out by boos.

The issue became so nettlesome for Bush, Reagan's principal opponent in the GOP primaries, that he tried to deflect it by saying that longtime Reagan adviser Casper W. Weinberger, now secretary of defense, was a Trilateralist.

Reagan responded blandly that Weinberger hadn't attended a meeting for a long time. He also gained the approval of anti-Trilateralists by saying that he wouldn't have 19 Trilateralists in his administration as Carter did.

Well, he doesn't. But those who thought the world could be made safe from David Rockefeller by having Reagan in the White House have another think coming.

According to well-placed White House sources, the president has heeded Rockefeller's request and will receive the three leaders of the commission when the Trilateralists convene in Washington March 29-31. These leaders are Rockefeller, representing North America, European chairman George Berthoin and Japanese chairman Takeshi Watanabe.

What's more, the Trilateralists will hear from two of the most prominent Reagan cabinet members -- Secretary of State Alexander M. Haig Jr., scheduled to be guest of honor at the commission's concluding dinner, and Weinberger, who resigned from the commission after the election.

There are lots of good reasons for the Reagan administration to see the Trilateralists. The membership, after all, includes influential industrialists who support many Reagan programs. And many would agree with the assessment of the commission's coordinator George S. Franklin that the Trilateralists have brought the Japanese into "constructive international dialogue."

One White House source said Reagan could hardly snub the Trilateralists at the same time he is likely to be asking the Japanese voluntarily to restrict imports into the United States.

But old fears die hard, and the far right is ever-vigilant for signs of creeping Trilateralism witthin the citadel. A well-placed White House official, confirming that the president would indeed receive the leaders of the commission, felt obliged to add this caution: "You better say this is a tentative decision. There may be an attempt to turn it around."