A medical officer of health, also known as a medical health officer, chief health officer, chief public health officer or district medical officer, is the title commonly used for the senior government official of a health department, usually at a municipal, county/district, state/province, or regional level. The post is held by a physician who serves to advise and lead a team of public health professionals such as environmental health officers and public health nurses on matters of public health importance.
The equivalent senior health official at the national level is often referred to as the chief medical officer (CMO), although the title varies across countries, for example known as the surgeon general in the United States and the chief public health officer in Canada.