The effects of modifier addition and temperature variation on the supercritical fluid extraction of nylon-6 and poly(1,4-butylene terephthalate) samples are discussed. The modifiers studied include hexane, chloroform, methanol, and benzene. The influence of experimental parameters, such as extraction temperature and pressure, static time, and supercritical fluid flow rate, are investigated systematically with both pure and modified carbon dioxide. The addition of a suitable modifier results in significantly enhanced extraction rates, particularly at low extraction temperatures. A simple experimental setup for the introduction of additional volumes of modifier during the extraction was developed and evaluated. Guidelines for the optimization of the supercritical fluid extraction of polymeric samples are given.