The treatment of home-based cancer patients with continuous infusion chemotherapy requires that complete courses of medication in pre-filled syringes are provided on an out-patient basis. The infusion must remain stable prior to use during refrigerated storage (up to 14 days) and during infusion from holster-worn ambulatory infusion pumps where the temperature of the infusion can reach 37 degrees C. In this study, polypropylene syringes containing interferon alpha-2b infusion (3 mega units in 6 ml) were stored at 4 degrees C. The infusion was analysed during storage by a qualitative gradient-elution high-performance liquid chromatography procedure. Over 14 days storage at 4 degrees C or 24 h storage at 37 degrees C, chromatographic changes occurred indicating interconversion between interferon monomers and possibly oligomer formation. Until further studies are completed we consider interferon alpha-2b unsuitable for inclusion in our home oncology programme.