Ethyl cellulose (EC) and deproteinized natural rubber latex (DNRL) were used to prepare a pseudolatex-base as a matrix membrane for ketoprofen patches. The pseudolatex-base was prepared using a homogenization and solvent removal method. Either polyvinyl alcohol or polysorbate 80 was used as surfactant and emulsifier. Polyvinyl pyrrolidone, glycerine, isopropyl palmitate, and dibutyl phthalate were used as a channeling agent, skin humectant, enhancer, and plasticizer, respectively. Ketoprofen was incorporated into the pseudolatex-base. All pseudolatex formulations were homogeneous and smooth in texture and elegant in appearance. The pH of pseudolatex formulations was 5-7, and the particle size was 487-787 nm. The viscosity and spreadability test showed the good characteristics of membrane. Stable colloidal dispersion was formed with a zeta potential of -35.18 to -51.55 mV. All pseudolatex formulations were formed into in situ membranes by solvent evaporation in a hot air oven at 70 +/- 2 degrees C. The mechanical test and moisture uptake were characterized, which significantly depended on ingredient. The in vitro release and skin permeation of ketoprofen from the pseudolatex-membrane were evaluated. The suitable pseudolatex-membrane was produced from a EC:DNRL ratio of 1:1 and provided a controlled release and suitable permeation patterns of the ketoprofen. Thus, these systems are essentially based on a matrix membrane made from polymeric pseudolatex systems.