Yuri Sucart entered the plea Thursday to one charge of conspiracy to distribute testosterone and five charges of actual distribution of the performance-enhancing substance. Sucart is free on $50,000 bail.
Rodriguez is serving a one-year suspension from baseball. He has said Sucart provided him with steroids when Rodriguez played with the Texas Rangers from 2000 to 2003.
In the Florida case, prosecutors say Sucart and others set up meetings between athletes and Biogenesis of America owner Tony Bosch. Some athletes were in high school.
Bosch cooperated with prosecutors and intends to plead guilty. Others charged in the case have pleaded not guilty.