The adsorption of different allergen extracts onto colloidal particles (nanoparticles and nanocapsules) made of polyisobutylcyanoacrylate (PIBCA) and polymethacrylate copolymer has been studied. A qualitatively analysis of the adsorption has been performed using both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting technique. These studies have shown that the adsorption onto PIBCA nanoparticles was not specific to certain types of proteins but that all kinds of proteins were adsorbed. The stability of the adsorption of a Dactylis glomerata extract onto PIBCA nanoparticles was studied in the presence of human serum. A slight desorption of D. glomerata allergens was observed only in the presence of a high concentration of serum in the incubation medium. The desorption observed under these conditions was the consequence of both the biodegradation of the polymer by serum esterases and the competitive displacement of allergens by serum proteins. The influence of the surfactant (Pluronic F 68) of the stabilizer (Dextran 70) used in preparing colloidal particles was also investigated.