Plymouth extend deal for Sunderland's Anderson
The Scotland international had been due to return to Wearside this week at the end of a one-month deal at Home Park.
Sunderland have retained the option of a 24-hour recall should they need cover for injury problems.
Argyle boss Paul Sturrock recently spoken of his admiration for the former Aberdeen defender.
"He's a model professional," Sturrock told reporters on Monday. "We'd like to keep him."