Poly(butyl cyanoacrylate) (PBCA) nanocapsules with an aqueous core containing bovine serum albumin (BSA) were prepared by interfacial polymerization in a W／O emulsion．The nanocapsule sizes and their distribution were measured by laser scattering technique and transmission electron micrography．The change of Zeta potential

encapsulation efficiency

drug loading and in vitro release of nanocapsules were investigated using BSA as a model drug. The experimental results showed that nanocapsules were approximately 200 nm in diameters

0.226 in polydispersity. Encapsulation efficiency and drug loading were depended on the initial BSA concentration in aqueous phase. When the concentration was 0.8 mg／mL

encapsulation efficiency and drug loading were 35％ and 0.485×10-9 ～mol／mg of polymer．With the increase in the wall thickness of nanocapsules

the release time of BSA in PBS solution increased．The release rate could be controlled through adjusting the wall thickness of nanocapsules.