CONFUSION REIGNS in "Henry IV, Part I," the disappointing inaugural production of the American National Theater at the Kennedy Center Eisenhower Theater.

As Sir John Falstaff himself might put it, this "Henry IV" is burdened with such a deal of skimble-skamble stuff it puts you from your think.

As directed by Timothy S. Mayer, the play suffers under the weight of eccentricity for its own sake, an incongruous pile of styles that vary erratically between tongue-in- cheek slyness and self-conscious portentousness.

The staging gives Shakespeare's play about the unending struggle for power such a fragmented feeling that a reading of the synopsis (provided with the playbill) is essential.

John Heard and John McMartin are vital signs in this production, but even they are often at sea amid the confusion of acting styles.

McMartin carries off the impressive physical feat of playing the weighty roles of King Henry and Falstaff, often in adjoining scenes. He gives the play its center, and, thankfully, the two roles keep him center stage for much of the 31/2-hour duration. McMartin's King Henry resembles a corporate chairman with Northeastern boardroom lockjaw, and though his bald wig and fat pads are unconvincing, the actor is mightily amusing as the heavily hyperbolic Falstaff, perpetually escalating the stakes in his tall tales. McMartin is particularly sharp in a tavern scene in which, performing an uproarious burlesque of the king, he caricatures and comments on his own performance.

Heard is boyish and mischievous as Prince Hal, the "nimble-footed madcap Prince of Wales," and is particularly able in his father- and-son scenes with McMartin, in which he visibly changes from ne'er-do-well truant to a chastened prince-with-a-purpose.

The rest of the cast performs unevenly. Bruce McGill is appropriately hotheaded as the rebel Henry Percy, known as "Hotspur," but his excessive tantrums bring him closer in spirit to a professional wrestler. Patti LuPone is stiff as Kate, the bored wife of workaholic, war-aholic Hotspur, though she is affecting in an odd scene in which she sings a folksong in those unmistakable "Evita" tones. And as Glendower, the Welsh rebel, Andreas Katsulas (in one of his four roles) is strong and striking.

Though most of their antics seem at odds with the more serious stuff, a few supporting players, many of them more accustomed to musical comedy, do well in superfluous roles, including talented Denny Dillon, who plays a barkeep, and Tony Azito, who adds his goofy style to a ribald music-hall scene-changer.

The show's surfaces are striking. Adrianne Lobel's set design is particularly memorable -- a towering black wall that folds to suggest various locales, with clever perforated drops that become windows and the moon. But Lobel has built blocky, squarish furniture of unfinished wood to go with it, so the effect is often more that of a Conran's warehouse than 15th-century England. James F. Ingalls' lighting is one of the most impressive parts of the evening, as subtly changing and enchanting as the northern lights.

The spare and quirky music is by '60s wonderboy Van Dyke Parks with Fredric Myrow, who orchestrated some sprightly synthesizer flourishes and diverting pieces for violin, cello and harp.

The climactic battle scenes are choreographed by the estimable B.H. Barry, who for some reason has opted to stage one fight in utterly unconvincing slow-motion, quickly followed by a this-town-ain't-big-enough-for- the-both-of-us showdown between Prince Hal and hotblooded Hotspur, in fast-forward.

But it's all too much, with too little at the center. Granted, the self-imposed task of this new theater company is to take liberties and risks. But shouldn't there be some discernible point and value to those risks? With "Henry IV," Mayer's muddle of affectations is ultimately of interest only to those in the playbill. They do not illuminate, and they are certainly not for the benefit of the audience, which is left to sit in the dark -- and leaves in the dark.

HENRY IV, PART I -- At the Kennedy Center Eisenhower Theater through April 20.