The work of Heric and Brewer (1969 Journal of Chemical Engineering Data, 14, 55-63) which involved testing a number of liquid viscosity correlations resulted in concluding that the McAllister (1960 A.I. Ch.E. Journal, 6, 427-431) model was the most accurate. However, the fact that the McAllister model is correlative in nature severely limits its practicality and usefulness. This is because costly and time-consuming data are required for the determination of the adjustable (or interaction) parameters contained in that model (Asfour, Cooper, Wu & Zahran, 1991, Industrial and Engineering Chemistry Research, 13, 1666-1669). This study reports the development of a generalized expression of the McAllister model for multi-component liquid mixtures, evaluation of the generalized McAllister model parameters, converting the McAllister model into a predictive model, and comparison of the predictive capability of generalized McAllister model with those of the GC-UNIMOD reported by Cao, Knudsen, Fredenslund and Rasmussen (1993a,b Industrial and Engineering Chemistry Research, 32, 2077-2087, 2088-2092) and with the generalized corresponding slates principle (GCSP) which was reported by Teja and Rice (1981 Industrial and Engineering Chemistry, Fundamentals, 20, 77-81). The comparison clearly indicated that the generalized McAllister model is consistently far superior to the GC-UNIMOD and the GCSP in predicting the viscosities of ternary, quaternary, and quinary liquid mixtures. This, no doubt, represents a significant accomplishment in the area of predicting the viscometric behaviour of multi-component liquid mixtures.