Unlike a normal packed bed, an expanded bed shows a distinct size distribution of adsorbentsalong the bed height, which certainly causes the nonuniform characteristics of bed voidage andvariation of fluid hydrodynamics and liquid dispersion alone the axial direction. For analysis,modeling, and prediction of the biomolecule adsorption performance in expanded-bed chromatography,the understanding of liquid dispersion along the bed height is fundamental andnecessary. On the basis of this background, axial dispersion in expanded beds for adsorbentswith a density difference and a log-normal size distribution was investigated. The tracer pulseresponsemethod combining in-bed sampling techniques was used to measure axial dispersionvariations along the bed height in a 20-mm-i.d. expanded bed with UpFront FastLine SPadsorbents as test particles. The local effective axial dispersion coefficients along the bed heightwere calculated and analyzed. There is a decreasing trend of axial dispersion along the bedheight at various liquid flowing velocities, which is more remarkable than that for those widelyused Streamline particles with a normal size distribution and a relatively uniform density. Anempirical correlation for the variations of effective axial dispersion coefficients is recommendedbased on the hydrodynamic performances within the bed also.