Hours: 1 a.m. to midnight Monday through Saturday; 1 to 111 p.m. Sunday.

Prices: Most appetizers $1 to $2, entres $5 to $10.

Cards: Amex, MasterCard, Visa.

On a canopy outside this spiffy restaurant is a simple slogan: ''A Place for Ribs.'' It's a fair description, because the Tony Roma menu features barbecued ribs and chicken and also offers up steak, London broil, a kabob, trout and hamburgers. Although the food here is far from outstanding, most of it is decent enough, especially in view of the reasonable prices, the attractive setting and the good service.

Although this is the only outlet in the Washington area, Tony Roma's is a national chain, and it's obviously a well-oiled operation, with quality control right on the mark and a staff that's been well chosen and well trained.

There's a big, handsome bar, and an adjoining area with tightly packed tables where you can eat. On a weekend night, they could call it the Decibel Room.

For quieter dining, you can opt for the back room, a good-looking area with comfortable banquettes and soft lighting. It has an opulent feel, despite the linen-less tables. (After all, when barbecued ribs are the house speciality, bare surfaces and paper napkins make a lot of sense.)

To start are onion rings, deep-fried in a special basket that packs them in a tall, irregular cylinder. The result is a veritable leaning tower of onions, with the $1.95 ''half loaf'' enough to satisfy four ordinary appetities. They're pretty good, the onions sweet and still a bit crunchy, but they're too oily to be championship contenders.

Chicken fingers are fine, the white meat moist and the dipping sauces flavorful, and so are the baked potatoes and french fries.

Both the St. Louis-style ribs and the smaller baby back ribs are of good quality -- reasonably meaty and free of excess fat, nicely glazed with barbecue sauce. The barbecued chicken may be even better than the ribs, with moist, flavorful meat and a slightly crisp skin. But the barbecue sauce served along side seems curiously mismated to the ribs and chicken -- it's so tart with vinegar as to drown out the delicate smokiness in the meats.

Among the rest of the entrees, the steak is big, juicy and cooked as ordered, but it's somewhat lacking in texture. The trout is a good buy at $5.95 and nicely fried, but we had one swimming in excess butter. Burgers are generous in size and char-broiled; however, the one we ordered medium rare was cooked nearly to well-doneness and wasa a tad greasy. The slaw is nicely crunchy.

If you carve a salad, though, eat one at home: The ''tossed'' salad is a mound of tired, ice-cold head lettuce glopped with ordinary dressing.