A gas chromatographic procedure for the analysis of fatty acids (as methyl esters) and glycerol (as isopropylidene glycerol) in oil paints is described. Molar ratios of selected fatty acids to the glycerol content were useful for characterizing lipids used in conservation. Evaluation of pigment interferences revealed that, of the pigments tested, only Paris blue, azurite and red lead had any measurable effect on the analytical results. Exposure of oil paint specimens to heat and light significantly increased the concentrations of most dicarboxylic fatty acids, whereas the amount of azelaic acid increased only slightly. Surprisingly, exposure to heat and light reduced the concentrations of saturated fatty acids in oil paints. Test results of samples from oil paintings were consistent with the trends established by the exposed oil paint specimens.