Do Scientologists use medical doctors?

Of course. The Church of Scientology has always had the firm policy of not diagnosing or treating the sick. Medical doctors are trained to deal with the physical aspects of illness and injury. A Scientologist with a physical condition is always advised to seek and obtain the needed examination and treatment of a qualified medical professional. Once under medical treatment, a Scientologist then addresses his illness or injury with auditing to handle any spiritual trauma or other factors connected with the physical condition which may have predisposed him to illness or injury.

There are also many medical doctors who are Scientologists themselves. More about that on scientology.org