The most common technique to produce nanoparticles involves evaporation of a polymer emulsion to obtain polymeric particles less than 500 nm in size. And since its introduction in the late 1970's, this process has been widely used for pharmaceutical applications to obtain clinically applicable drug delivery systems. Many adjustments and adaptations of this technique have been made, attempting encapsulation of a wide variety of bioactive compounds. The advantages and drawbacks of the single-emulsion and especially double (multiple)-emulsion techniques are discussed in the present review article. It covers patent and patent applications literature, as well as peer reviewed research papers discussing pharmaceutical polymer-based nanoparticles obtained by the double emulsion-solvent evaporation technique using preformed polymers.