In this paper multivariate calibration was used in conjunction with NIR-Fourier transform Raman spectroscopy for determination of the total degree of unsaturation in vegetable oils. For this purpose, different vegetable oils and some mixtures were employed as calibration standards. A calibration model based on partial least squares (PLS) was constructed and used to analyse oils with iodine values ranging from 17 to 130. This methodology is rapid, simple and can be easily used in quality control laboratories or to monitor industrial process on line. (C) 2001 Elsevier Science B.V. All rights reserved.