Temperatures have been recorded in a cave at Creswell Crags, Nottinghamshire, to assess the effects of fire on the thermal micro-climate of a cave. The fires were located in the entrance and to the rear of the main cave chamber to examine how the positioning of the fire may affect the cave temperature pattern. Airflow and smoke movement were assessed qualitatively. It was concluded that fires near the cave entrance did not affect interior temperatures. A fire at the rear of the cave would generate warmth but excessive amounts of smoke, so only ember fires would be possible if the cave were to be suitable for habitation.