The hot water resistance of polyurethane sealants of various compositions was investigated. Cast and cured samples were assessed by measurements of: water swelling resistance; compression recovery; extension-compression fatigue resistance; and by hand peel tests from concrete substrates. The influences of polyol composition, fillers, antioxidants and adhesion promoters were studied. The sealants prepared using a hydrophobic polyol exhibited superior hot water resistance to those containing polypropylene glycol. Compromises between adhesion, cohesion, water swelling and thermal oxidation are discussed. 13 refs.