Abstract: A chimney fire extinguisher includes a small diameter narrow conduit removably insertable through a small aperture in a chimney wall. A source of fire extinguishate under pressure is coupled to one end of the conduit for delivery of the extinguishate through the conduit. A sprinkler head is fixed to the opposite end of the conduit for insertion through the chimney wall aperture. The sprinkler head comprises an enclosed chamber, a restrictor for restricting the flow of extinguishate from the conduit into the chamber, a small orifice for spraying extinguishate from the chamber into the chimney and a fusible seal for normally sealing the sprinkler head orifice. In an alternate embodiment the sprinkler head orifice is not sealed but is only loosely covered. A temperature sensor is provided for sensing the temperature within the chimney. A valve which is opened in response to the detection of chimney temperatures in excess of about 1200.degree. F.