Results are reported from a study on the in vitro separation and identification of leachables from three different polymer-based dental filling materials by using a combined method of gas chromatography and mass spectrometry. The median number of separable organic leachables in these materials was between 14 and 22. Of these organic leachables the following were identified and quantified: DL-camphorquinone, 4-dimethylaminobenzoic acid ethyl ester (DMABEE), drometrizole, 1,7,7-trimethylbicyclo[2,2,1]heptane, 2,2-dimethoxy[1,2] diphenyletanone (DMBZ), ethyleneglycol dimethacrylate (EGDMA), and triethyleneglycol dimethacrylate (TEGDMA). Three of the leachables have previously been shown to provoke allergy. The range of log P(ow) values (representing the lipophilicity of these compounds) varied between 1.09 and 4.20. By multivariate data analysis, selected leachables from the tested materials were shown to separate into characteristic patterns. The results contribute to a characterization of potential hazardous compounds in polymer-based dental filling materials.