The Chinese want boys, and the Canadians want girls. If they have enough money, they come to the United States to choose the sex of their babies.

Well-off foreign couples are getting around laws banning sex selection in their home countries by coming to American soil - where it's legal - for medical procedures that can give them the boy, or girl, they want.

"Some people spend $50,000 to $70,000 for a BMW car and think nothing of it, but this is a life that's going to be with us forever," said Robert, an Australian who asked that his last name not be used to protect the family's privacy.

He and his wife, Joanna, have two boys. Now they want a girl. Australia only allows gender selection of embryos to avoid an inherited disease.

The United States' lack of regulation means a growing global market for a few fertility clinics. These businesses advertise in airline magazines or post Web sites aimed at luring clients worldwide.

Opponents say this amounts to medical tourism for designer babies and should awaken lawmakers.

But one doctor who offers embryo selection for about $20,000 says he is serving the marketplace and helping Nature, not playing God. People will be less alarmed as sex selection becomes more routine, said Dr. Jeffrey Steinberg of the Fertility Institutes of Los Angeles and Las Vegas.

"It's new. It's scary. We understand that," Steinberg said. His Web site features an image of a Chinese flag alongside information about sex selection. "Near 100% (99.99%) effective gender selection methods to help balance families," the Web site promises.

"We basically want them to know it's available," Steinberg said of the international push. The Web page on sex selection generates 140,000 hits a month from China, he said, and the only country outpacing China's interest is Canada.

In a recent week, his clinics performed the procedure on eight women from abroad and consulted with 12 new foreign patients from China, Germany, Canada, the Czech Republic, Guam, Mexico and New Zealand, he said.

Most couples are affluent, Steinberg said. But some, like Australians Robert and Joanna, have moderate incomes. Robert, 30, works as a construction supervisor and Joanna, 27, is a part-time secretary.

The couple visited Steinberg's Los Angeles clinic in May and, including airfare, will spend half their annual income to have a female embryo implanted in Joanna's uterus.

The procedure, which Steinberg also offers as an add-on service for infertile couples, determines the gender of a batch of fertilized eggs and implants only embryos of the wanted sex. This process - called preimplantation genetic diagnosis, or PGD - is more widely used to screen for genetic diseases.

"The Chinese like boys. Canadians like girls. Every country is different," he said, adding that the boy-girl preference balances out at 50-50 when all his clients are added together.

Foes call it "consumer eugenics" and say it opens the door to a future where parents will choose their babies' hair color, eye color and potential to grow tall enough to play basketball.

"What you're saying is it's better you don't exist than be the wrong gender for my family. And that's a shocking assertion," said Matthew Eppinette, director of research at the Center for Bioethics and Human Dignity, a Christian bioethics group.

The method can prevent sex-linked inherited diseases. But when it's used solely to help a couple get a coveted girl or round out a family of daughters with a wanted son, the practice is controversial, even among doctors who specialize in reproductive medicine.

"We don't do that. Sex is not a disease," snapped Yury Verlinsky, director of the Reproductive Genetics Institute in Chicago.

The American Society for Reproductive Medicine says sex selection of embryos is clearly ethical when the method is used to prevent genetic disease. But the professional group discourages its use for choosing one gender over another. The group says the practice risks reinforcing sexism in society and diverts medical resources from real medical needs.

While many countries prohibit sex selection techniques without a medical purpose, the United States has no such ban.

"We are one of those few countries in the world where sex selection using PGD isn't regulated," said Susannah Baruch, director of the Reproductive Genetics and Public Policy Center at Johns Hopkins University. "It's certainly a magnet for couples for whom this is important."

The Johns Hopkins center is leading an effort to collect data on how many sex selection procedures are performed in the United States and why they are performed. No one tracks those numbers now.

Another group, the Center for Genetics and Society, is calling for regulation of the practice and its marketing.

"Right now the market is driving practices rather than social and ethical concerns," said Sujatha Jesudason of the center. "People who have money to pay for it are getting the children of their choice."

Steinberg said his clinic requires international couples to be in the United States for only five days. His office can work with a clinic in the couple's home country to monitor the woman's preparatory injections with fertility drugs that stimulate egg production.

"Even though it's illegal there, the illegal part happens here," he said. Once the woman produces eggs, she and her husband fly to the United States. In the U.S. clinic, the eggs are extracted, fertilized with the husband's sperm and monitored while they grow to eight cells each.

A lab technician extracts one cell from each embryo for genetic analysis. If it's the preferred gender, it will be implanted in the client's womb along with one or two other embryos, all selected for gender, to increase chances of a successful pregnancy. The client decides whether unused embryos will be frozen, donated for research or destroyed.

The Australians, Robert and Joanna, see gender selection as no different ethically and morally from in vitro fertilization for infertile couples. They reject the term "designer babies."

"It's not like we want some 6-foot-tall, blue-eyed Brad Pitt lookalike," Robert said. "I naturally have something and my wife naturally has something and it's taken out of our bodies and then you're getting a doctor to mix it together and put it back in. ... We're not messing around with God the creator."