Every day around lunchtime, Marines in camouflage uniforms descend on the tiny Virginia town of Quantico, where they are welcomed with open arms by the two dozen businesses that line Potomac Avenue, the town's main street.

For the past three years Marines from the huge base that surrounds Quantico were not often seen in town during the day because of a corps policy that banned wearing the service's camouflage work uniforms off the base. Marines wearing "cammies" could drive through town but were forbidden to leave their cars except to pump gasoline or for emergencies. Merchants complained about lost revenue.

Now Quantico's commanding general, in a move to help the town's businesses, has lifted the camouflage ban, making Quantico the only civilian community in the country where Marines may go about their business in "cammies," according to Capt. Jay C. Farrar of the Marine Corps Headquarters in Arlington.

The new policy, effective on an experimental basis until March 31, has brought smiles to the lips of merchants in Quantico, whose eight square blocks and 700 residents are almost wholly dependent on business from the 97-square-mile base and its 7,000 Marines.

"We have a very different situation here from anyplace else," said Katherine E. Bolognese, who, with her husband, manages a men's wear store in Quantico. "We're surrounded by the base on three sides, and because of the [Potomac] river [that borders the town to the east], we can't grow anymore. You have to go through the base to get out of town."

"It's definitely helped business and it's helped the young Marines," said Quantico Mayor Lively C. Abel, who owns a sandwich shop and a coin laundry.

"Our carry-out business has picked up right much since they changed the policy," said Raymond M. Lowry, manager of Domino's Pizza shop. "I'd say there's been a 15 percent increase, especially around lunchtime."

Marines also cheered the move. "It's about time the Marine Corps got something right," said Lance Cpl. Wayne L. Oyer, 21. "If you need gas or something from the store you can run down here to pick it up, drop off some cleaning, grab a bite to eat. It's convenient."

Merchants in town, about half of whom run restaurants serving sandwiches, pizza and hot food, said they think the ban was ordered three years ago because Marines would frequently take extended lunch and beer breaks in town.

By requiring Marines to change into more formal uniforms or civilian clothes, the policy effectively discouraged visits to town, the merchants said.

Windows along Potomac Avenue now feature a bright yellow placard announcing the new policy and warning: "This is a privilege. Please DO NOT ABUSE IT and spoil it for others."

The message is in line with a Sept. 17 order from the base's Maj. Gen. David M. Twomey, stating that any violations of the order -- such as wearing "cammies" into town outside the prescribed hours of 6:30 a.m. to 6:30 p.m. -- would result in the order's revocation.

Town merchants and officials say they will help the Marines enforce the new policy. "If we see them in town after 6:30 we'll give them a ride back to the base," said Mayor Abel, who had lobbied Marine officials for the change for years.

"I asked them to treat us like they would the rest of the base," Abel said. "We want to stay on good terms with the Marines. This has been a real shot in the arm for local merchants."

Paul Tierney, a restaurateur who grew up in Quantico, said, "You go by the Marine Corps rules and regulations or you don't get along. We've been here 36 years and we love the Marine Corps and we abide by it."