If you are an employee in a medical office with access to medical records should you protect your friend by telling him that you know that his partner has tested positive for AIDS?

It is a HIPAA violation to reveal any patient's Protected Information. AND, you should really notify your employer BEFORE your friend's partner is seen in the medical office, so YOU are not involved with that case. If that notification was not made (so you would not be tempted to peek at a record), then you stillMUST uphold HIPAA.