This investigation focuses on the study of the thixotropy behavior of crude oil-polyacrylamide emulsions. A wide range of crude oil and polymer concentrations were covered. Crude oil concentrations of 0-75% by volume and polymer concentrations of 0-10(4) ppm were used. Two polyacrylamides of Alcoflood polymers, AF1235 and AF1285, were examined. RheoStress RS100 rheometer from Haake was employed to Study the thixotropy behavior of crude oil-polymer emulsions. Measurements of thixotropy were conducted under the controlled rate mode. The aqueous solutions of Alcoflood polymers show thixotropy behavior. AF1235 aqueous solutions show lower hysteresis rheograms and thixotropy area than the aqueous solutions of AF1285. Polymer concentration shows strong influence on the ramp-up and ramp-down curves. The crude oil-polymer emulsions behave in an antithixotropy response instead of thixotropy behavior experience for the polymer aqueous solutions. The yield stress values of the crude oil-polymer emulsions increase strongly with polymer concentration for ascending and descending cycles. However, for polymer concentration of less than 1000 ppm, crude oil shows strong effects on the emulsion yield stress values for the ramp-down cycles. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 867875,2009