The flow and creep compliance properties of reduced-fat yoghurts containing whey protein concentrate (WPC), microparticulated whey protein, or a blend of both fat replacers were determined and compared to those exhibited by a full-fat yoghurt (FFY). The flow behaviour of all the yoghurts was described by the Ellis equation. Rheological parameters such as instantaneous compliance (J0), mean compliance (Jm), mean retardation time (tm), and Newtonian viscosity (ZN) were useful to explain structural characteristics and changes in the protein network of the reduced-fat yoghurts. The yoghurt made with WPC showed flow and viscoelastic properties that resembled more closely those of the FFY. r 2004 Elsevier Ltd. All rights reserved.