A modified Herschel-Bulkley model [E. Mitsoulis, S.S. Abdali, Flow simulation of Herschel-Bulkley fluids through extrusion dies, Can. J. Chem. Eng. 71 (1993) 147-160] predicts an infinite apparent viscosity at vanishing shear rate. Furthermore, the dimensions of one parameter depend on another parameter. In this contribution, we propose a generalized model based on earlier work by De Kee and Turcotte [D. De Kee, G. Turcotte, Viscosity of biomaterials. Chem. Eng. Commun. 6 (1980) 273-282] and on the work of Papanastasiou [TC. Papanastasiou, Flows of materials with yield, J. Rheol. 31 (1987) 385-404] to solve the problems associated with the modified Herschel-Bulkley model. Compared to the responses of the Papanastasiou model and the modified Herschel-Bulkley model, the proposed generalized model provides the expected improvements and is capable of predicting successfully the rheological behavior (viscosity and yield stress) of Carbopol 980 dispersions. (c) 2005 Elsevier B.V. All rights reserved.