The long-term sensitivity and calibration stability of liquid ionizationchambers (LICs) has been studied at a local and a secondary standardsdosimetry laboratory over a period of 3 years. The chambers were transportedseveral times by mail between the two laboratories for measurements. The LICsused in this work are designed for absorbed dose measurements in the dose rateregion of 0.1-100 mGy min-1 and have a liquid layer thickness of 1 mmand a sensitive volume of 16.2 mm3. The liquids used as sensitive media inthe chambers are mixtures of isooctane (C8H18) and tetramethylsilane(Si(CH3)4) in different proportions (about 2 to 1). Operating at apolarizing voltage of 300 V the leakage current of the chambers was stable andnever exceeded 3% of the observable current at a dose rate of about1 mGy min-1. The volume sensitivity of the chambers was measured to be ofthe order of 10-9 C Gy-1 mm-3. No systematic changes in theabsorbed dose to water calibration was observed for any of the chambers duringthe test period (σ<0.2%). Variations in chamber dose response withsmall changes in the polarizing voltage as well as sensitivity changes withaccumulated absorbed dose were also investigated. Measurements showed that theLIC response varies by 0.15% per 1% change in applied voltage around 300 V.No significant change could be observed in the LIC sensitivity after a singleabsorbed dose of 15 kGy. The results indicate that the LIC can be made toserve as a calibration transfer instrument and a reference detector forabsorbed dose to water determinations providing good precision and long-termreproducibility.