The shear stress-shear rate relationship of six food thickeners from guar gum, modified starch and xanthan gum in homogenised and pasteurised full cream (HPFC), skim milk (SKIM) and ultra-high temperature or ultra-heat treated full cream (UHT) was investigated at 20 degrees C. For all the thickened fluids, shear stress increased as the rate of shear increased from I to 100 s(-1). An increase in solids content increased the viscosity, density and yield stress. The type of milk significantly influenced) < 0.05) the density of the fluids and SKIM milk could yield the densest fluids. Irrespective of the type of milk, the guar gum-based thickened fluids (Guarcol (TM) and Supercol (TM)) were the most viscous, and they exhibited the highest yield stress. Among the three types of milk, the most viscous thickened fluids or thickened fluids with the highest yield stress were obtained when SKIM was the dispersing medium. The Herschel-Bulkley models were found to be the most suitable rheological models for the shear stress-shear rate data. The regression parameters obtained are valuable in calculating the weights of the thickener and dispersing medium for clinical uses. Crown Copyright (c) 2007 Published by Elsevier Ltd. All rights reserved.