Long after the witching hour at the Middle East Supper Club, Faten Salama slinks onstage from the kitchen. She has come, the oud player shouts, "all the way from Cairo, Egypt," which is maybe why she is late.

Judging by crowd response -- a dark, bewhiskered fellow urging her on in Arabic, another chap, wide-eyed, clenching a wet cigar -- she is clearly worth the delay.

The musicians, a foursome wedged at the back of the stage beside a copper amphora sprouting peacock feathers, plunge headlong into a dance tune as patrons pound their tables. Faten Salama jerks her shapely hips and smiles -- a vision in bugle beeds and swirls of white, moving and shaking under blinking blue bulbs. Her arms, braceleted, swivel; her stomach, netted, writhes.

"She's big movie star in Egypt," says Ahmad X. Khatib, the plump and stately owner, his snaggletoothed grin looming over the stuffed grape leaves. Yelling into a visitor's ear, he can barely be heard over the furiously beating dumbeq, the madly jangling req, the strumming of the electrified oud, the plucking of the kanun and the frenzied clapping of many hands. "I have the films. I will show them to you."

That ancient pastime, belly dancing, is alive and well in Washington. It has endured since a day some 5,000 years ago when, as legend has it, Queen Cleopatra, the first of several by that name, happened on a Nile snake and was moved by the way it slithered.

Four establishments hereabouts -- the Aladdin at the Quality Inn Northeast, Alkhayyam near Embassy Row, the Astor downtown and the Middle East Supper Club at Tysons Corner -- currently feature lithe young women, rhythmically rippling as the customers dine. But, as fans of the dance are quick to insist, the diversion is not what most folks think.

"People just have to remember that it is an ethnic art form," cautioned Athanasia Georgianis, who learned her moves in Cairo and does them three nights a week at the Aladdin. "It's not meant to be go-go or erotic or anything like that. I hold my art form in high esteem."

At the Middle East Supper Club, Fatem Salama's legs twitch out of her whirling see- through skirt; her polished pink toenails flash. Spangled fringes dangle in synch from her ample chest and hip belt. Her flushed face shines with sweat; she bites a strand of hair. "This song now," Khatib shouts helpfully, "very popular in Saudi Arabia."

The dance is dubbed, variously, raks al sharqi in Arabic, and danse orientale or danse du ventre (literally "dance of the belly") in French.

The music, a maelstrom of syncopation, quarter-tones and counterpoint, often concerns romance -- "Boy, oh, boy, I've been burned by the fire of love," goes the lyric of a standard titled Ilwalad Soyourir ("The Small Boy") -- and always gets sung in an exotic desert idiom.

And though it moves in mysterious ways, the dance boasts a basic element that's easily understood. "Hizzy ya wiz!" (loosely translated from the Arabic as "Shake it, old goose!") is a favorite cry of spectators. The unschooled observer, however, is hard-put to know what to watch for.

Fatem Salama, for instance, is known among the cognoscenti to mix modern dance and jazz steps with Egyptian undulations, but she doesn't seem much different from more traditional dancers like Sudesh, a computer whiz by day who, long blond hair cascading down her back, works the early show at the Aladdin; or Nazira, a law-firm receptionist who took the stage on a lark the other night, in street clothes, at Alkhayyam. (Many of the dancers, like Sudesh and Nazira, are American by birth and heritage.)

Jean Parker, a Department of Labor economist who doffs her veil as Zarifa Sa'id, explained: "In the Middle East, it's mostly a pelvic dance that features muscle isolation. I guess the most succinct definition would be the isolation of body muscles in combination with drum rhythms, so that your feet could be stepping in four-four time, your hips might be doing triplets, and your shoulders might be punctuating measures or phrases in the music along with your chest, while you might want to pick up some of the melody with your arms."

Athanasia added: "There are basically two styles, Arabic and Turkish. The Arabs work the hips mostly, and the Turks mostly use the upper torso of the body. Also, the Turks like to go down on the floor."

Upstairs at the Astor, amid the paneled veneer and Dayglo stained glass of Athens West, all suffused in smoke and chiaroscuro, Turkish-style dance seems the order of the night, and the music's mainly Greek. The other evening, as the bouzouki player stared at the wall and the fellow at the keyboard made electric disco noises, Melina and then Sumi took the floor -- or, rather, burnished it with their thighs.

Going by their facial contortions, that was the climax of their performances, both of which featured pouting looks and lots of arching back. Melina -- tall, dark and handsome -- tossed her veil at one of the customers and bit her forefinger at another, a gent with a pate like Kojak's. He languidly nodded and waved.

Sumi, in spiked high-heels and purple- sequined Valkyrie wings, vied for the attention of some visitors by clicking together her zills -- small cymbals -- an inch or two from their faces.

"Oh," said Sam Pantazopoulous, co- owner of the Astor, "it's jut a joke with them, you know. Lots of times, the dancers kid around with the customers."

The Astor's food runs a gamut of standard Greek fare, most of it indifferently prepared, and the clientele seems to be composed largely of tourists, the odd couple or two, and refugees from a hard day at the office. But aficionados of belly dancing know it as a place where the two shows a night (which also feature a crooner with his top three shirt buttons undone) start right on schedule.

That also seems true of the Aladdin, a darkened railroad flat of a room with neo- Crusade decor, which opened a couple of weeks ago off the Quality Inn Northeast's lobby. But patrons should be wary of lackluster service and the restaurant's standard menu of mundane fare, not well done, at prices that can only be described as chutzpah: A meal of a couple of drinks and "New York Strip Steak," perhaps packed in plastic by a chain store, costs $20 plus. At the reserved tables near the front, though, folks seemed to be enjoying the Middle Eastern cuisine, which was to be found on another menu, not offered to a visitor.

Alkhayyam and the Middle East Supper Club seem the liveliest of the places, though it's probably not wise to set your watch by the show schedule. Alkhayyam is brightly lit and has an outdoor cafe; the Middle East is somewhat cave-like; both are done up in a quasi-Moorish scheme.

If you arrive at either place before midnight, plan to stay long. At both restaurants, which serve such Middle Eastern staples as shish kebab and falafel along with standard American fare, the regulars fill any lulls in the action by getting onstage themselves.

That's what happens at the Middle East Supper Club, after Faten Salama finishes her 20-minute show, after the musicians play "Happy Birthday," with everyone joining in, for a woman named Miriam, and after the prominent wall clock shows one in the morning. A stocky, balding man ascends the stage and, with a great flourish, looses a blizzard of dollar bills from his pockets. Then, as the patrons clap along, he starts to dance in the manner of Anthony Quinn as Zorba.

"He's Greek," says Ahmad Khatib, once a resident of Jerusalem, as he pours Arabic coffee from a samovar. A lady in a red dress joins the man. "She's Egyptian," Khatib says. Soon two younger men climb up, and all them dance together. "They're Palestinian. They all come here -- from Palestine, Saudi Arabia, Syria, Jordan -- from all the Arab nations."

NAVEL MANEUVERS A list of restaurants that feature belly dancing. Reservations are advised for a ringside seat. ALADDIN -- At the Quality Inn Northeast, 1600 New York Avenue NE. Belly dancing Thursday through Saturday. 526-4700. ALKHAYYAM -- 2605 24th Street NW. Belly dancing Wednesday through Monday. 265- 7233. ASTOR -- 1813 M Street NW. Belly dancing nightly. 331-7994. MIDDLE EAST SUPPER CLUB -- 8240 Leesburg Pike. Belly dancing Thursday through Saturday. 893- 9004.