The two France internationals face potential prison terms of up to three years each if convicted.
Ribery and Benzema were not present as the trial opened in Paris on Tuesday, and then was adjourned until January for procedural reasons.
The players are accused of sexual relations with an underage prostitute.
Self-described escort girl Zahia Dehar has alleged that Ribery flew her to Munich as a birthday present to himself in 2009, when she was under 18. She says she lied to the players and told them she was an adult.