We examine the influence of cationic poly(amidoamine) (PAMAM) dendrimers on capillary electroseparation-UV analysis of proteins. PAMAMs adsorbing to the capillary surface suppressed the wall-adsorption of proteins; meanwhile, PAMAMs added to the buffer exhibited selectivity toward proteins. Presence of 3 x 10(-4) g/mL PAMAM generation one (G 1.0) in 30 mM phosphate, at pH 2.6, rendered significant enhancement in separation efficiency; the merged peaks of myoglobin and trypsin inhibitor were separated. Moreover, the protein-dendrimer interactions changed the inherent UV absorbance profiles of proteins. UV-Vis study showed that the absorbance of cytochrome C and transferrin increased at the detection wavelength of 214 nm; their detection sensitivity enhanced by 2.44 and 2.01-folds, respectively, with addition of 5 x 10(-4) g/mL PAMAM G 1.0.