Concern over the stability of air-supported structures under fire conditions has been expressed by those involved with safety of persons in places of assembly and over the safety of contents by those concerned with insurance of property. Tests have been conducted to investigate the behaviour of a structure with high and low level perforations, the effect of smoke and fires on escape, the characteristics of the fabric material and the fire fighting problems. From these tests it was found that smoke is vented by any opening made in the structure, and normal exits may become smoke-logged when they are opened. The structure remains inflated with small fires even though the fabric is punctured, aided by the buoyance effect, but collapses quickly with a large fire. Fires can be put out from inside if they are small and from outside if the collapsed fabric lies flat on the ground.