It was just a kick. A hobby for a bunch of fraternity brothers -- Phi Delta Theta -- at the University of Maryland 30 years ago. They got together with their acoustic guitars and made some folk music.

Then the musicians, dubbed the Hard Travelers, found themselves playing at the Cellar Door nightclub in Georgetown, opening for such acts as the Journeymen (who later became the Mamas and the Papas), Ian and Sylvia, and the Chad Mitchell Trio, featuring John Denver.

In 1964, the Travelers had a hit single, plus an album and a tour lined up. But they backed out. Decided to "pursue our individual careers," says acoustic guitarist Kenn Roberts.

Roberts went into commercial real estate. Guitarist Buddy Renfro became a documentary film director. Banjo player Ed Winsor was a fiscal analyst. Bassist Mike Ritter did documentary film editing, and won an Academy Award.

Five years ago, on a whim, the four decided to get back together for a small gig at the Maryland Inn in Annapolis. It sold out. There were old groupies from the gone-but-not-forgotten Cellar Door in the front row. It went so well, the performers decided to scrap those individual careers and become full-time musicians. Winsor dropped out shortly after that and was replaced by banjo player and guitarist Mack Bailey. They recorded two albums andtoured up and down the Eastern Seaboard. Last year, they even went to Taiwan, representing the state of Maryland.

Many of their concerts are benefits. They have written and recorded a couple of songs about the Chesapeake Bay that caught the attention of Gov. William Donald Schaefer, who enlisted their help in the state's bay cleanup campaign.

Their biggest beneficiary by far, though, is the Cystic Fibrosis Foundation. In the past two years, the Hard Travelers and Friends concerts have raised more than $70,000 for the cause. This year's concert features country superstar Emmylou Harris, pop duo Fat City, folk ensemble Schooner Fare, jazz legend Charlie Byrd and guitarist Pete Kennedy.

The Hard Travelers and Friends third annual Cystic Fibrosis Foundation benefit is Wednesday at 7 p.m. at Merriweather Post Pavilion. Tickets are $10 to $20 and available at Ticketron. For information, call (800) 543-3041.