Bradley Waite wanted to bring his adult daughter to this country from Jamaica, but couldn't prove they were related — she was born out of wedlock, so his name was not on her original birth certificate.

U.S. immigration officials did something that is unusual but becoming more common: They asked for DNA tests.

Waite grumbled over the $1,000 cost as he submitted to the testing several weeks ago. "We needed more proof, but I wish I didn't have to take it, because it cost too much money," said the 52-year-old construction worker in New York City.

Genetic tests are playing a larger role in the U.S. immigration process. In some cases, the government is asking for DNA proof of a family connection; in other cases, applicants are offering to undergo testing in hopes of speeding up a process that often takes years. Either way, the applicant must bear the cost.

Though U.S. Citizenship and Immigration Services says it does not track how often DNA testing is used in immigration and citizenship cases, testing companies say that in recent years they have seen a sharp increase.

Generally, U.S. citizens can petition to bring spouses, parents, children or siblings here, while legal permanent residents can apply for spouses and unmarried children.

DNA testing in applications began in the 1990s and remains "extremely rare" in the hundreds of thousands of petitions processed every year, said immigration services spokesman Chris Bentley.

"We'll consider all other documentation first," Bentley said. "If something is missing, or we need to verify a relationship, we can ask for the test."

The DNA is used only for immigration purposes and is not put into a database, Bentley said. Some lawyers representing immigrants argue that tests are overused and wonder what the government is doing with the information.

"DNA has its upside and downside," said Daniel Sharp, legal director for Carecen, a Hispanic advocacy group in Los Angeles that helps immigrants with applications. "There is a concern about how much information the government has."

Seattle-based Genelex Corporation has gone from administering about 10 DNA tests per month in 2001 to about 40 per month over the past year, said Kristine Ashcraft, director of client relations. Several other companies reported similar increases.

"Many immigrants are realizing the test could cut down on the length of an application," said Ashcraft.

That is what motivated Joseph Mataley, a Ghanaian who paid $1,500 for testing on himself and his four young daughters soon after he filed their U.S. residency applications. Immigration officials did not request such tests.

It was a lot of money for Mataley, who works two jobs in Denver, but "it probably would have taken another year without doing the DNA so quickly," he said. He was reunited with his daughters in April after a three-year application process.

To take the test, the petitioner in the U.S. uses a government-approved company, which collects a saliva sample. The overseas relative then heads to the nearest U.S. embassy, where an official gathers a sample and sends it to the company. The cost generally is at least $600 for two people.

Immigration officials say that when they request DNA, it is usually for cases where applicants from poor countries do not have birth certificates, or when discrepancies raise suspicions of fraud.

Immigration lawyers say many government requests are based on hunches. They complain that some clients are asked to take tests even though their paperwork is complete.

Molly Short, director of U.S. Committee for Refugees and Immigrants in Albany, N.Y., is appealing a government request that a Liberian refugee undergo DNA testing to prove two toddlers are hers.

The woman, evacuated from a refugee camp last year, has valid birth certificates, Short said. Short said it is ridiculous that a woman who makes $8 an hour cleaning hospital beds should have to take expensive tests.

Still, many immigrants will do what it takes to improve their chances.

Eduardo Colin, a 49-year-old Mexican construction worker in Los Angeles, took a DNA test three weeks ago along with his mother. Colin's mother is a U.S. citizen, entitling Colin to citizenship even though he was born and raised in Mexico City.

"This is going to help my case," Colin said. "It will prove that my mother is my mother."