Abstract: Flexible polyurethane foams are described which are the product of reaction under foam producing conditions of a combination of (a) an aromatic polyisocyanate; (b) a polyether polyol with the optional use of a minor amount of a cross-linking polyol; (c) antimony oxide; (d) a polyhalogenated aromatic compound; and (e) a hydrated inorganic salt.The foams have flame retardant properties superior to those of the prior art while at the same time having physical properties equal or superior to the prior art materials. Accordingly, the foams of the invention meet very stringent tests for fire retardance required of seat cushioning, mattresses, and like materials in aircraft, institutions such as hospitals, convalescent homes, and the like.