Abstract: Taylor dispersion analysis (TDA) is commonly performed in fused silica capillaries using capillary electrophoresis instrumentation. The sample is introduced into the capillary, however, instead of applying a potential the sample is mobilized using a Poiseuille flow/by applying pressure. The parabolic flow profile leads to dispersion of the analyte while traveling through the capillary. The degree of analyte dispersion is related to the diffusivity of the analyte. This makes TDA a powerful tool for size measurements of molecules ranging from low molecular weight drug substances to nanoparticulates of the size of ~200 nm. The presentation will highlight how TDA can be used for sizing of drug substances and delivery systems and for assessment of molecular interactions (somewhat similar to affinity CE) using cyclodextrins, micelles and liposomes as examples. Based on TDA, exploiting a selective interaction, we have developed Flow Induced Dispersion Analysis (FIDA) for quantification of biopharmaceuticals in plasma. Examples on the application of this alternative approach to ELISA will be given.