In this work, vapor-liquid equilibria (VLE) calculations for a continuous mixture are carried out. The Peng-Robinson EOS is employed, and a new approach for parameter evaluation is proposed, using group contribution methods. This approach was possible through the use of a convenient choice for the characteristic continuous index. Multi-indexed continuous mixtures are focused on, which has been avoided in the literature probably because of the mathematical complexity of such modeling. Two algorithms were proposed for VLE calculations (flash with P and T fixed, bubble and dew points) and three kinds of continuous mixtures (linear paraffins, polyunsaturated fatty acids (PUFA) and oil fractions) were analyzed. (C) 2000 Elsevier Science S.A. All rights reserved.