The solid-liquid phase diagrams of two binary mixtures of saturated fatty acids, formed by caprylic acid (C-8:0) + myristic acid (C-14:0) and lauric acid (C-12:0) + myristic acid (C-14:0), were measured using high pressure microscopy in the range of 0. 1-90 MPa. It is shown that unlike for other long chain alkyl compounds such as alkanes the phase diagrams are only slightly affected by the pressure, even in very large pressure ranges such as studied in this work. The modeling of the measured phase diagrams was attempted using an approach previously developed by the authors for n-alkane mixtures. It is here shown that this model can provide an accurate description of the high pressure solid-liquid equilibrium of fatty acid mixtures. (C) 2007 Elsevier B.V. All rights reserved.