This work aims at studying the interaction between human serum albumin and different generations of dendrigraft poly-l-lysine (DGL) in physiological conditions. The binding constants and stoichiometry of the interaction were successfully determined using frontal analysis continuous capillary electrophoresis. The effect of generation on the interaction was evaluated for the five first generations of DGL. An increase of the binding constant accompanied with a decrease of the HSA:DGL (1:n) stoichiometry and a decrease of the cooperativity with dendrimer generation was observed. These findings were in good agreement with the increase of ligand (DGL) size, the increase of electrostatic ligand-ligand repulsion, and the localization of two negatively charged interaction sites on the HSA. The effect of the ligand topology (linear vs dendrigraft) on the HSA interaction revealed that linear poly(l-lysine) leads to much lower stoichiometry compared to DGL of similar molar mass due to much higher flexibility and contour length.