When the 7,000 participants in the Prince Hall Shriners' parade strutted down Pennsylvania Avenue at midday yesterday, they were led by one of their newest members -- D.C. Mayor Marion Barry. He had been "created," as they say, just a few days ago.

Surveying the array of marchers in their colorful robes and uniforms from the reviewing stand in front of the District Building, Barry said, "It's great to have the Shriners in town. They brought a lot of people and a lot of money."

Before they leave Saturday after their week-long convention, the35,000 Shriners, their wives, girlfriends and family members will have spent more than $12 million, organizers estimate.

They call themselves the nobles of the Ancient Egyptian Arabic Order Nobles Mystic Shrine of North and South America and Its Jurisdictions, Inc.

They give their leaders titles like imperial potentate. They belong to temples with such names as Sheik Temple No. 98 of Riverside, Calif., El Hasa Temple No. 28 of Cleveland, and Kadesia Temple No. 135 of Colorado Springs.

The men wear red fezzes, and some sport dangling earrings that look like shields. But these men with their secret handshakes and good-time-at-the-fraternity-house spirit also give to charities. They award scholarships. They contribute to hospitals and medical research.

The predominantly black organization counts among its 50,000 nationwide membership Supreme Court Justice Thurgood Marshall, Mayors Tom Bradley, Maynard Jackson and Coleman Young of Los Angeles, Atlanta and Detroit, and musicians Count Basie and Lionel Hampton. Founded in 1893, the black Shriners are not affiliated with the predominantly white Shriner groups in the country.

Their presence here this week marks the first time the Prince Hall Shriners have convened in Washington in 10 years, and yesterday was their day on Pennsylvania Avenue.

Simon Peter Burkes is the oldest Shriner here. He's 102. He joined the Prince Hall Masons in Bainbridge, Ga., 73 years ago after his father told him that the only organization worth belonging to was the Masons.

Being a Mason is the first step to becoming a Shriner. But before attaining Shrinerhood, you must be at least a 32nd degree Mason. Burkes is a 33rd degree Mason and is attending his 26th Shriners convention.

He calls the Shriners "the playhouse for the Masons and their families. It's where the boys just have fun."

Leaning on his cane and peering over his wire-rim glasses, Burkes is the wise man of the convention. He says he has never remarried since his wife died 40 years ago because "you only get another one like her in heaven." He credits his long life to "never eating too much and eating less meat."

Weldon Willis, a member of El Hasa Temple No. 28 in Cleveland, has been a Shriner for 15 years. His grandfather was a Mason. His father was a Shriner.

He plans his vacation every year for the third week in August so he can attend the annual convention. One year, he drove some 42,000 miles to participate in various activities of his Masonic brothers in various cities.

"It becomes very expensive," he said. "But, it's worth it. You become a member. You get very dedicated to the whole cause. Your vacation, everything is centered around the activities that are going on. You really must be dedicated to do these kinds of things."

The public's view of the Shriners is limited to their charitable work. They refuse to discuss their secrets, like the secret handshakes, the secret code words and the secret initiation ceremony called "The Creation."

"We are an organization with secrets," said Archie Anderson, deputy imperial promotion director from Denver, Colo. "But we let you know who we are. We give to hospitals, cancer research, sickle cell research. Just yesterday we gave $30,000 to the NAACP."

Even the women's auxiliary of the Shriners, called the Daughters of Isis, is secretive. "I like the work of the Daughters of Isis," said Susie Elliott, past commandress of Al Zabir Court No. 141, Daughters of Isis, of Kalamazoo, Mich.

What is that work? She hesitated. "It's kind of a secret thing," she said. "However, we do a lot of charity work."

Washington businesses welcome the Shriners, who have booked rooms at 16 hotels in the city.

The Sheraton Washington hotel is headquarters for the convention. "It's a nice piece of business for the city and for us," said John Alden, Sheraton manager. "My typical image of the Shriner was a good time and drinking. But I found them to be very well behaved. We are very pleased to have them."

City officials estimated 40,000 people lined Pennsylvania Avenue yesterday to watch the Shriner parade.

"I haven't seen anything this colorful since the Mardi Gras," said Nevers Jefferson, as he watched a drum-and-bugle corps adorned in red, yellow and green uniforms.

The parade disrupted traffic, which had to be rerouted. Cabbies were irked. Many bus riders complained that they had to wait nearly an hour for a bus.

"It's a mess," said one Northwest Washington woman who finally gave up waiting for a bus and took a cab home.

"It's an inconvenience, but it's our own fault," said James Gough, who had brought his family to town from Virginia to visit the Museum of Natural History, but ended up watching the parade instead. "We should have listened to the radio first. I think everyone has a right to parade. If you can't do that in the nation's capital, where can you do it?"