Maurice Hines has been tap-dancing professionally for almost 50 years. And after all that time, he's come to a very firm conclusion: He's really, really tired.

There's the groin muscle problem that won't go away. The lower-back aches. He recently directed and performed in a variety show in Las Vegas that put him onstage 14 times a week. Dance can be tough on any body, even one as elegantly long and streamlined as Hines's. But he knows: Tap exacts a special toll. The toe positions put constant strain on the knees, the metal cleats radiate vibrations up the legs and into the back. It's hard not to hurt.

And so, Maurice Hines, 56, says he's done with all that. "This summer, I told my mother, 'I'm tapped out,' " he says. "I gave my tap shoes to her."

Hines sounds serious, and it'll be a shame if he is. He and his brother, Gregory, nurtured and sustained the great American art of tap for a generation. They followed in the extraordinarily deft footsteps of such pioneers as the Nicholas Brothers, Sandman Sims, John Bubbles and Sammy Davis Jr. Along with dad Maurice Sr., they played Johnny Carson's "Tonight Show" 37 times. They did Ed Sullivan, Mike Douglas, "The Hollywood Palace." There they are tearing it up in Francis Ford Coppola's 1984 film "The Cotton Club," playing a pair of feuding siblings (much as they have been in real life). And both men have danced up and down Broadway. Gregory has four Tony nominations, Maurice one.

It's Maurice Hines's dancer energy that makes him watchable still as gambler Nathan Detroit in Arena Stage's production of "Guys and Dolls," which opened last night. The part mainly demands that he show his chops as a comic actor. He's billed as the star, but the big, showy numbers in the classic Frank Loesser musical go to Alexandra Foucard as Nathan's frustrated showgirl sweetie, Adelaide, and to real-life married couple Brian and Diane Sutherland, as Sky Masterson and missionary Sarah Brown. Hines dances only briefly. But his loose-limbed Nathan--"My character, he's hyper all the time," he says--appears ready to boogie at any moment.

Coaxed into taking the part by director Charles Randolph-Wright, a longtime friend, Hines is happy to have a second crack at Nathan. He toured in the role 20 years ago with Richard Roundtree, Debbie Allen and Leslie Uggams. "Guys and Dolls" was a transitional project then, helping Hines transform himself from nightclub hoofer to full-fledged multi-hyphenate: actor-singer-dancer-choreographer-director.

"I remember I was so scared," he says over morning coffee in Arena's foyer. "I learned that show in two days. Every word of dialogue. I walked around Riverside Park [in New York] mumbling to myself. The neighbors must have thought I was crazy."

Hines says he modeled his first Nathan on his Uncle Sid, a somewhat surreptitious character who ran numbers in Hines's native Brooklyn. In Randolph-Wright's Arena production, he says, he's channeling his late Uncle Doc, who ran a successful limo service--an "adorable," gregarious soul who attracted seven special women (wink) to his funeral a few years ago.

Hines is a pretty gregarious character, too. After decades of performing everywhere from the Catskills to the Playboy Club to Hollywood, he's got a mental photo album brimming with Legends He Has Known. He mentions opening for Judy Garland, working with Lena Horne, Carol Channing, Dinah Washington. The brothers played Vegas with Ella Fitzgerald (she was obsessed with her weight, Hines recalls; she stayed in her dressing room all day, eating diet candies and slugging Frescas).

He won't talk much, however, about Gregory, a man from whom he was once inseparable. "I never discuss my personal life," he says firmly, his lively demeanor grown suddenly cool.

But of course he does talk, little by little, as a man inevitably will when the subject is profoundly painful and sweet, the memories so self-defining.

The Hines boys were never far from the business. Their grandmother was a showgirl at the Cotton Club. Their father was a musician and a bouncer at the Audubon Ballroom in New York (later infamous as the site of Malcolm X's assassination), who took them to hear big bands. Pushed by his mother, Alma, now 82, Maurice took tap lessons and started performing professionally at the age of 7; he'd come home and teach steps to Gregory, almost three years his junior. Soon they were performing together as the Hines Kids, then as the Hines Brothers and eventually, with Maurice Sr. on drums, as Hines, Hines and Dad.

The family act broke up in 1973. Personally and professionally, it was a calamity for the brothers. Gregory moved to Los Angeles and later admitted to experimenting with drugs; Maurice got depressed and ate. He ballooned more than 50 pounds over his current weight (171), which he now maintains with a disciplined regimen of treadmill exercise and one meal a day.

For years, they refused to speak to each other, the bitterness festering.

"Maurice and I are very different," Gregory told Ebony magazine in 1992, in the most elaborate public explanation of their differences. "And also there is a real truth to sibling rivalry. The fact that my brother and I are in the same profession, that we worked together in the same act for almost 30 years, are all contributing factors. So much of our relationship was in the act. And maybe with my brother and me, the act might have been what kept us together. And when it was gone, it was tough for us to find a reason to spend time together."

In fact, it was Maurice who rescued his brother's career. At Maurice's urging, Gregory returned to New York in 1977 and tried musical theater. They worked side by side twice more, in the 1978 Broadway revue "Eubie!," based on the career of jazz composer Eubie Blake, and later in "Sophisticated Ladies," based on the music of Duke Ellington.

Gregory got the notices in both productions, effectively turning Maurice into the Other Brother, the Dom DiMaggio of song-and-dance men. Gregory earned the first of his four Tony nominations in "Eubie!" (he ultimately won, for playing Jelly Roll Morton in "Jelly's Last Jam" in 1992). He also went on to star on TV and in such movies as "White Nights" (1985), with Mikhail Baryshnikov, "Tap" (1989), "Waiting to Exhale" (1995) and a self-named but short-lived CBS sitcom two seasons ago.

Maurice tried Hollywood, too, but not much came of it. He spent nine years working as a choreographer, doing videos and the occasional feature. He hated the pace (slow), the vicious competition, the general "amorality" of the business.

The theater has been more hospitable. In 1986, overcoming his own longstanding critique of Broadway's racism, Hines conceived, directed, choreographed and starred in "Uptown . . . It's Hot!," a revue of African American music that earned him his Tony nomination. He's done national tours of "Satchmo," "Harlem Suite," "Sophisticated Ladies" and "Jelly's Last Jam," in which he succeeded Gregory in the title role.

He's in a particularly fecund period now. He recently directed and choreographed a show, "Broadway Soul Jam," in Amsterdam, which was followed by a Radio City Music Hall production in Las Vegas (Hines is the first African American director in Radio City's history). And just before "Guys" he was in Cuba, directing a musical called "Havana Nights," with an all-Cuban cast. He's now putting together a hip-hop version of "Alice in Wonderland" for Radio City called "Yo, Alice" that, he hopes, will debut sometime next year with Sinbad as the White Rabbit.

"My life is the happiest it's ever been," he says. "I've grown as a man. It took six or seven years for me to eliminate all the stresses in my life. And that includes family [stresses]."

That's Hines's oblique way of saying he's mended his relationship with his brother. They're talking now. More than that, Gregory and Maurice Sr. will be coming to town to catch him in "Guys and Dolls" (Mom is recovering from a heart bypass and can't leave Las Vegas).

Even more than that, he says he'd like to complete the circle with Gregory: He'd like to perform with him again. "I wanted Greg to do Sky [opposite his Nathan], but my brother won't do eight shows a week," Maurice says, laughing. "Theater's too tough. He likes to wait around four hours for 30 seconds of dialogue."

As for hanging up his tap shoes, Hines sounds resolute about it. Done. Finished. Take a bow. Then again . . . when he completed the national tour of "Jelly's Last Jam" five years ago, he declared himself done with acting, too. Maybe it's the lifelong hoofer in him. Can he really leave without one more curtain call?

CAPTION: A rift with his brother, Gregory, mended, Hines says his life is "the happiest it's ever been."

CAPTION: Maurice, left, and Gregory Hines in 1984's "The Cotton Club."