Steelers running back Jonathan Dwyer was fined $21,000 for lowering his helmet into Bears safety Chris Conte in the second quarter Sunday.
Dwyer was found to have delivered a blow with the crown of his helmet while running outside the tackle box.
There was no flag on the play.
The crown-of-helmet rule began this season. Titans running back Jackie Battle became the first player to be fined for the violation one week ago.