A preparation method for nanoparticles based on an emulsification of a benzyl alcohol solution of a polymer in a hydrocolloid-stabilized aqueous solution followed by a dilution of the emulsion with water, was developed. Several process parameters were varied, including the concentration of poly(vinyl alcohol) or gelatin used as stabilizing colloids in the external phase, the concentration of nanoparticle polymer in the internal phase and other process variables such as the external/internal phase ratio and the viscosity of the external phase. By increasing the percentage of poly(vinyl alcohol} to 27 .5 % in the external phase, it was possible to produce nanoparticles as small as 70 nm in diameter. Poly(vinyl alcohol) could be replaced by gelatin and the smallest nanoparticles obtained under these conditions had an average size of 700 nm. It was demonstrated that the nanoparticles can be loaded with the cytostatic drug chlorambucil (8.52% m/m) with an entrapment efficiency reaching 60%.