The heat keeps going on and on for Saigon.

Miss Saigon, the international musical smash created by French, British and American artists, celebrates its ninth anniversary on Broadway April 11 with performance No. 3,761.

Penned by French composer and lyricist Claude-Michel Schonberg and Alain Boublil (who were also the librettists) along with American lyricist Richard Maltby Jr., the musical is inspired by Madame Butterfly, but with an American G.I. falling for a young Vietnamese girl during the 1975 fall of Saigon in the Vietnam War.

Nicholas Hytner directed the sometimes pageant-like production, first in London and then in New York City, where it opened in 1991 at the Broadway Theatre. Bob Avian staged the musical numbers.

The musical's centerpiece visual moment involves the illusion of a helicopter taking off at the American embassy in Saigon, separating lovers Kim and Chris. Lea Salonga and Jonathan Pryce both won Tony Awards for recreating their respective London roles of Kim and the venal Engineer, a Eurasian opportunist during the conflict.

The casting of the white, British Pryce in a biracial role was protested by the American acting community in 1990-91 and producer Cameron Mackintosh famously threatened to cancel plans for the multi-million dollar staging. The acting community, including Actors' Equity, gave in.

It is thought that some 28 million people worldwide have seen Miss Saigon in London, New York, on tour and in resident stagings in Tokyo, Amsterdam, Copenhagen, Budapest, Sydney and beyond.

The current Broadway company features four original cast members from 1991: Alan Ariano, Francis J. Cruz, Sylvia Dohi and Ray Santos.

The current cast includes Luoyong Wang as The Engineer, Deedee Lynn Magno as Kim, Will Chase as Chris, C.C. Brown as John, Edmund Nalzaro as Thuy and Margaret Ann Gates as Ellen. Elizabeth Paw plays the role of Kim at certain performances.

Tickets are $20-$80. The Broadway Theatre is at 53rd Street and Broadway. For tickets, call (212) 239-6200.