This study was intended to carry out qualitative and quantitative analyses of fatty acids in plaque and saliva. Samples of plaque and saliva from 10 volunteers were analyzed for fatty acids by gas-chromatography and gas-chromatography/mass spectrometry. The sample preparation procedure allowed specimens from individual volunteers to be analyzed. The results showed the plaque contained C14.0, C15.0, C16.0, C16.1, C18.0, C18.1, C18.2, C20.0 acids and the saliva contained C16.0, C18.0, C20.0, C16.1, C18.1, C18.2 acids. The concentration of fatty acids in plaque was 35.17 +/- 7.723 micrograms/mg (dry weight); and that in saliva was 13.23 micrograms/ml. Quantitatively, C18.1 and C16.0 acids were the largest fatty acids. These findings imply that the origin and role of the fatty acids in plaque and saliva may be different.