Stone's former maid, Angelica Castillo, filed a wrongful termination lawsuit Monday in Los Angeles County Superior Court.
The complaint says Castillo injured her back carrying Stone's groceries in June. It alleges Stone ignored doctor's orders to give Castillo time off for her back to heal, then fired Castillo because she was slowed down by the injury.
Stone's lawyer didn't respond to requests for comments.
The actress is also facing a lawsuit from a former nanny in a dispute involving overtime pay.