The uptake and the retention of hypocrellin B(HB)by murine ascitic hepatoma(AH)cells was measured as function of incubation time.The data of uptake fitted the Freundlich adsorption isotherm very well over a wide range of hypocrellin B concentrations.The uptake occured very quickly and reached the maximun in 3 min at 37℃.The adsorped HB was quite difficult to be released to phosphate buffered solution whereas the releasing process was enhanced significantly by the addition of serum into the bath medium.The fluorescence quenching experiments using fatty acid probes located at different depths of cellular membranes indicated that the HB molecules have the trend inserting into the deep hydrophobic domains.