Eighteen months ago, former Green Beret Robert Sweitzer was diagnosed as having skin cancer, a disease he attributes to his exposure to Agent Orange during a 1968 tour of duty in Vietnam.

A few years ago, Sweitzer's son was born with a birth defect that doctors say may also have been caused by Agent Orange, a herbicide linked to cancer, birth defects and other ailments.

Illnesses are not Sweitzer's only reminders of Vietnam. He has had to overcome the grief of losing some his closest friends in the war, and he initially faced difficulty in finding a job in "a society that did not consider us respectable."

But today, Sweitzer, the executive director of a Baltimore nursing school, and seven other Vietnam veterans, most of whom hold professional or management jobs, plan to begin a seven-day, 200-mile walk from Southern Maryland through the Washington area to Baltimore. The march will "help show the people of Maryland that the Vietnam War was worthwhile," Sweitzer said.

"For the first time I am proud to be a Vietnam veteran," he said. "When I got back, I took my uniform off. We were not respected, but finally that is beginning to change."

The trek is part of a five-year drive to help raise $3 million for a proposed Maryland Vietnam Veterans Memorial in Baltimore, expected to be dedicated on Memorial Day next year.

"Several of my childhood friends never came back from Vietnam; this will be my way of letting them know I never forgot them," said Michael Smith, one of the marchers, who served as a Marine courier transferring supplies and munitions in South Vietnam. "It's also a park for the living, a place where people can take their families and reflect back on what we all went through."

The planned memorial -- a three-foot-high, wall-like structure fashioned from white marble and pink granite and commissioned by the state legislature in 1983 -- is scheduled to adorn Federal Hill, overlooking the Inner Harbor. It will bear the engraved names of the 1,010 Marylanders who died in Vietnam. The slanted wall, capped in white granite, will be low so that visitors will have to bow, kneel or crouch to read the names.

The marchers say they hope the memorial will help destroy what they describe as myths about Vietnam veterans. "There has been too much emphasis on the fact that people came back and couldn't get it back together," Smith said. "But there are a lot people who are successful now who served in the war, and not enough attention has been paid to them."

The veterans hope to raise $300,000 in pledges and contributions from this week's walk as part of their long-range drive to raise $750,000. The state has allocated $2.25 million for the renovation of the Federal Hill site, said Thomas Shaner, a marcher, who now owns a public relations firm.

The group, which calls itself "The Last Patrol," raised $50,000 in a similar walk last year.

"We had no intention of raising money then," said Shaner, a University of Maryland School of Journalism graduate who served as an information officer for Stars and Stripes during the war. "People would just pull up and give us money right on the road -- people who told us they had lost friends or relatives in the war."

Almost $30,000 has been pledged for this week's march by donors who agreed to contribute a set amount for each mile the veterans walk, said marcher Paul Kozloski. "We're right on schedule, except we haven't received that much support from Prince George's and Montgomery counties. I guess people there identify more with the District than they do with Maryland."

The patrol plans to set out at 8:30 a.m. and to walk for 12 hours a day, spending nights at motels along the way. After a helicopter ride this morning from Baltimore to Point Lookout in St. Mary's County, the walkers plan to head for Calvert County and to reach Prince George's on Wednesday.

The patrol intends to collect a "ceremonial sample of earth" from each county and to carry the soil to the memorial site in Baltimore, Shaner said. The group is scheduled to stop at the Vietnam Veterans Memorial here Thursday and to arrive in Baltimore on Sunday for a ceremony at Federal Hill.

"We build our own memorials," Sweitzer said. "We build them to recognize each other, and we don't ask anyone to build them for us."