The companies claim that a better biological match will mean better sex, less cheating, longer-lasting love and perhaps even healthier children.
"How many dating services can you think of where they can suggest you might have better children?" said Eric Holzle, founder of ScientificMatch.com, one of the first online dating sites to use DNA.
Holzle wouldn't reveal membership numbers, but GenePartner, a Swiss company that works with matchmakers and dating sites, has tested more than 1,000 people, according to chief scientific officer Tamara Brown. Some were already coupled and took the test out of curiosity.
The GenePartner Test is $99, and will be offered at the dating site sense2love.com when it relaunches next month.