Abstract: A fresh air vent for building into the hearth of a fireplace is constructed with the shape and heft of a hearth brick. It has a body and lid of heavy-gauge steel, the body replacing a hearth brick in the hearth, and defining a screened top opening to a tubular flange extending most of the depth of the vent so as to establish a secure connection to an air duct without the use of tools. The lid is hinged to the back of the body, and has slightly inclined end walls passing through and retained in slots in the top of the body to establish frictional engagement therewith when the lid is open.