Neil Simon's "Biloxi Blues" is the most irresistible Broadway comedy to come to town since Neil Simon's "Brighton Beach Memoirs," which was pretty irresistible to begin with.

Those who look to the theater for a solid night's entertainment -- a perfectly reasonable expectation, after all -- have been getting the short end of the dramatic stick this season. For the next eight weeks, at least, they have a place to go -- the National Theatre, where "Biloxi Blues" began an eight-week stay last night. Simon has always known how to make us laugh. Lately, he has also been reaching our hearts. Set in a southern army camp in 1943, "Biloxi Blues" may be the most touching play ever written about the rigors of basic training.

Its hero is one Eugene Morris Jerome, Simon's alter ego, who successfully managed in "Brighton Beach" to navigate the rocky shoals of adolescence. But he's still got a lot of growing up ahead of him. At the start of "Biloxi Blues," the second installment in the playwright's projected autobiographical trilogy, he looks the future square in the eye and declares with characteristic ingenuousness, "There were three things I was determined to do in this war. Become a writer, not get killed and lose my virginity."

"Biloxi Blues" presentsitself initially as a raucous service comedy, old territory for Simon. Early in his career, as a writer on the Sgt. Bilko TV series, he exploited the indignities andabsurdities of barracks life for broad laughs. This time, he is intent on finding the humanity in the ordeal, as well. Eugene has to learn to cope with rotten chow, a tyrannical drill sergeant, Army discipline and fellow recruits, who are as likely to sing in their sleep as pass wind on the parade ground. But all the while he's really forging a sense of values.

When, on 48-hour leave, Eugene discovers himself in the arms of a prostitute, fighting off the jitters and the overpowering scent of his own Aqua Velva, he fumblingly learns something about sex. And when, later at a USO dance, he strikes up a conversation with a sweet southern Catholic girl, it dawns on him that maybe sex and love are not the same thing. Out in the bewilderingly wide world for the first time, Eugene instinctly assumes the best tactic is to stay neutral -- "like Switzerland."

The biggest lesson he will learn, however, is that ultimately you do have to take a stand, get involved, listen to your conscience. In that, he has a mentor -- an intellectual Jewish recruit, Arnold Epstein, who bucks the irrationality of Army routine every step of the way, even though it lands him perpetual latrine duty. "Once you start compromising your thoughts," Epstein warns him, "you're a candidate for mediocrity."

More than just Simon's version of "You're in the Army Now," "Biloxi Blues" is the chronicle of a likably goofy kid becoming a decent young man. And that extends its appeal immeasurably. The play is bathed in the warm nostalgia that all of us, in the rosier corners of our memories, like to reserve for the waning of our innocence.

The production at the National may not boast a performer with the marquee power of Matthew Broderick, who created the role of Eugene on Broadway. But the present Eugene, William Ragsdale, is every bit as engaging. The discrepancy between what the character knows, which is not a lot, and the worldliness to which he aspires could make him a wise guy or a boob. But Ragsdale steers a delicate course down the middle, so that we are almost always laughing with him, never at him.

Although "Biloxi Blues" deals with anti-Semitism and a case of homosexuality in the barracks, not to mention the usual sexual drives of men in olive drab, director Gene Saks handles the material with extraordinary finesse. It may sound misguided to talk of the delicacy of the endeavor, especially when the blue-tinted epithets start flying. A certain crudeness has always qualified men's dealings with one another, all the more so when they are cooped up in close quarters. Saks and his actors acknowledge that. At the same time, though, they delve beneath the bravado to show us the fears and insecurities of recruits who are actually trembling in their army boots.

There isn't a weak link in the cast. As the half-crazed drill sergeant with a steel plate in his skull, John Finn is seemingly the martinet of every draftee's nightmares. But there is a wellspring of compassion in the character and Finn's bark proves more intriguingly complex than his bite. Andrew Polk gives the slump-shouldered Jewish intellectual a sad dignity under duress. And John Younger, David Warshofsky, and John C. MacKenzie are splendid as the fellow soldiers, who would not necessarily be out of place in the gorilla house at the zoo. But even they go well beyond the usual smelly, bullying stereotypes.

Women play secondary roles in "Biloxi Blues," but some of Simon's most affectionate writing is reserved for them. Kathy Danzer's prostitute may not have a heart of gold, but she's not all brass, either. She treats Eugene with whimsical amusement, recognizing that what is business as usual for her is a big event for him. And there's a lovely contribution by Marita Geraghty, as one of the 14 available schoolgirls in nearby Gulfport, all of whom, Eugene notes ruefully, are "handcuffed to nuns."

His gawky courtship of the pretty girl is a disarming illustration of the self-conscious encountering the naive to the scratchy strains of a Victrola record. In addition, the scene deftly counterbalances the crassness confronting Eugene elsewhere. The army is shoving him into manhood, but part of him remains a starry-eyed boy, dazzled by a first kiss.

Like Simon, himself, I suspect. Ever since he began writing about his family and his youth, his plays have acquired a sense of wonderment and tenderness. The jokes are richer, more revelatory. The characters have gained vital human dimensions. America's shrewdest comic playwright is fast becoming one of the most generous.

On more than one count, "Biloxi Blues" allows a starved theatergoer to take heart.

Biloxi Blues, by Neil Simon. Directed by Gene Saks. Sets, David Mitchell; costumes, Ann Roth; lighting, Tharon Musser. With William Ragsdale, John Finn, Andrew Polk, Kathy Danzer, Marita Geraghty, John C. MacKenzie, Michael McNeill, David Warshofsky, John Younger. At the National Theatre through Aug. 3.