Wax precipitation measurements on 16 North Sea oil mixtures have been used to improve the model of Won for prediction of liquid-wax phase equilibria. It is shown that the amount of was precipitated as a function of temperature at atmospheric pressure can be predicted with reasonable accuracy using regular solution theory for the liquid and solid phases. The solid-phase solubility parameters must be somewhat increased as compared with the solubility parameters of normal paraffins and the assumed amount of heat liberated during the liquid-wax transition has to be reduced considerably as compared to the melting enthalpies of pure normal paraffins