There is provided a predominantly open-cell polyurethane foam obtained from a predominantly open-cell polyurethane foam-forming reaction medium which comprises: a) at least one polyol; b) at least one polyisocyanate; c) at least one catalyst; d) water; e) a predominantly open-cell polyurethane foam-forming amount of at least one surfactant which is a balanced, substantially linear polyether-polysiloxane ABA′ block copolymer; and, f) optionally, at least one additional component selected from the group consisting of other polymer and/or copolymer, chain extender, crosslinker, non-aqueous blowing agent, filler, reinforcement, pigment, tint, dye, colorant, flame retardant, antioxidant, antiozonant, UV stabilizer, anti-static agent, biocide and biostat.