Polyurethane potting compounds based on hexamethylene diisocyanate-trimethylol propane (HDI-TMP) adduct (Component "A") and polypropylene glycol, polyethylene glycol and castor oil (Component "B")were prepared as potential compounds for the fabrication of haemodialyzer. The setting characteristics of the potting compounds having isocyanate index 2.0 are better than those compounds having 1.35. The aging stability of PEG and PPG based potting compounds are poorer than those of castor oil based potting compounds. Appreciable hydrolytic, oxidative and chemical stability could be observed with castor oil based potting compounds of HDI-TMP adduct. © 2001 Kluwer Academic Publishers.