Group F streptococcus is a commensal of the gastrointestinal tract. A 68-year-old man had persistent fever following endoscopic biopsy of a subcarinal lymph node. He subsequently developed group F streptococcal bacteremia and a mediastinal abscess. The patient was successfully treated with administration of vancomycin and aztreonam and incision drainage. Group F streptococci are an emerging source of procedure-related infection with a predilection for abscess formation. This is a rare case of postprocedure group F streptococcus mediastinal abscess.