(FORTUNE Magazine) – In Asia, Hong Kong film producer Raymond Chow, 62, is known as Mr. Kung Fu, after his string of awesomely cheap, highly profitable action pictures. Chow has now worked a slight variation on this genre to produce Teenage Mutant Ninja Turtles. Instead of stars like Bruce Lee and other human bone crunchers, his new stars are Donatello, Leonardo, Michaelangelo, and Raphael, four nunchako-wielding reptiles, portrayed by actors in heavy carapace. The costumes were created by American Muppet master Jim Henson's Creature Shop and the characters by cartoonists Peter Laird and Kevin Eastman. The movie has taken the U.S. by storm, part of the turtle craze sweeping preschools nationwide. Since opening in late March, it has already become the highest-grossing independent film in history. In its first three weeks, box offices around the U.S. hauled in some $90 million, much of it from shrieking, turtle-crazed kids who qualified for half-price tickets. Chow, who founded his Golden Harvest studios 20 years ago, gambled $14 million on the ninja turtle movie, 20 times more than the tab for some of his kung fu actioners. Though he'll get that investment back many times over, he says the turtles' super-success won't tempt him to do bigger films in the future. Unlike some of his actors, his feet are firmly on the ground. As he likes to remind: ''It's a business. If you lose money, you can't make your next picture.'' Cowabunga indeed.