Central Health says medical information was mistakenly faxed as an email to a 1-800 number instead of a 1-866 number.
It says the faxing was part of routine auditing of doctors' billings and happened between May and August of this year.
Central Health says it's looking at ways to prevent similar incidents in the future and that patient care was not affected.
Information erroneously sent included copies of referrals and physician consultations.
Central Health says the person who mistakenly received the files says they did not view or share them before contacting the authority.