It is unclear what stimulus properties and sensory systems contribute to the discrimination of fat content in foods. Fluid dairy products containing 0·5 to 36% fat were rated on category scales for “fat content”, “creaminess”, and “pleasantness” under various conditions. In the first experiment, perceived fat content of the stimuli was not changed from normal conditions when visual and olfactory inputs were removed. In a second experiment, the stimuli were altered by the addition of a textural agent, such that their viscosities were all approximately equivalent. Elimination of olfactory input again had no effect on ratings of “fat content”. Addition of a textural agent greatly enhanced the apparent “fat content” of the lower fat samples, though it did not fully compensate for the perceived differences amongst the stimuli. These experiments strongly support the concept that perceptions of “fat content” in these products is largely attributable to textural properties, such as viscosity, sensed within the oral cavity.