Russell is a former LSU star who was released by Oakland after being the No. 1 draft choice in 2007. He entered the plea Tuesday in court in Mobile. He is charged with felony possession of a controlled substance, codeine syrup.
Authorities have said he did not have a prescription for the drug and that he was arrested July 5 at his home as part of an undercover investigation.
A hearing in his case is set for Aug. 11.