That Eiko and Koma, a Japanese-born couple now based in New York, are extraordinary performers is beyond challenge. Whether the pair, who have prompted increasingly admiring critical attention over the five years they have resided in this country, have yet found a performance vehicle commensurate with their abilities, remains moot. Such doubts, at least, are the outcome of "Trilogy," their most recent, 60-minute opus currently on view at Baltimore's Theatre Project (which has resumed the presentation of dance events with this production).

Eiko, 29, and Koma, 33, studied law and political science in Japan until, in 1971, they joined the radical theater group of Tatsumi Hijikata. After forming their own partnership the next year, they studied with the avant-garde master Kazuo Ohno, and subsequently in Europe and in this country, with a Wigman disciple, with jazz historian Mura Dehn, and with former Judson Dance Theater choreographer Elaine Summers. Since 1976, they have premiered and toured five evening-length works of their own, involving music ranging from Bach and Schubert to Beatles, New Wave and Third-World folk music.

In "Trilogy," Eiko and Koma appear with their bodies wound in frayed strings and tatters; in addition, they are plastered head-to-foot, including faces, in white flour paste. When the stage light first makes them visible, it is a shattering image. What inevitably leaps to mind is Hiroshima -- these must be charred, pitiably mutilated victims of cataclysmic disaster. Their movements are no less pungent in impact: In silence, at an incredibly slow pace, they stumble and grovel and roll, with seeming weightlessness and infinitesimal degrees of nuance.

Yet what follows never lives up to the promise of the first startling moments. "Cell," the first of the trilogy's sections, concentrates on a kind of infantile groping; "Fission" has the couple embracing and doing a primitive dance; in the finale, "Entropy," they don lobster-red shoes and bibs and put on a cabaretlike "performance" with song and mock-ballet. All this might be interpreted as an evolutionary cycle of human movement, but over an hour's span it seems mighty thin and uneventful, and the initial imagery is never satisfactorily extended or clarified. One leaves longing to see Eiko and Koma in material that would put their rare gifts to more fruitful use.