Blackstock, an unrestricted free agent, agreed to terms Monday. He started four games last season and appeared in eight others, recording 17 tackles. The NFL gave Blackstock a four-game suspension for using a performance-enhancing substance.
The Bengals also re-signed defensive lineman Orien Harris, a second-year pro who appeared in 14 games last season.
Terms of the deals with Blackstock and Harris weren't disclosed.
Copyright 2009 by The Associated Press