Abstract: A fire fighting foam formulation includes a non-foam forming amount of a saponin, such as a tri-terpene type saponin. The formulation may be an aqueous film forming foam (of either the alcohol resistant type or non-alcohol resistant type) which use a synthetic hydrocarbon surfactant as a foaming agent, a fluorocarbon surfactant to suitably lower the surface tension, and a non-ionic hydrocarbon surfactant to lower the amount of fluorocarbon surfactant required. The saponin significantly improves the heat resistance of the foam formulation when applied to fires, and can eliminate the need to use the non-ionic hydrocarbon surfactant. The saponin can replace part of the hydrocarbon surfactant component of the formulation so that a reduced amount of hydrocarbon surfactant is required in the formulation. The preferred concentration range of saponin in the formulation is between 0.3% and 1% by volume.