When a food is eaten to satiety, its reward value decreases. This decrease is usually greater for the food eaten to satiety than for other foods, an effect termed sensory-specific satiety. In an fMRI investigation it was shown that for a region of the orbitofrontal cortex the activation produced by the odour of the food eaten to satiety decreased, whereas there was no similar decrease for the odour of a food not eaten in the meal. This effect was shown both by a voxel-wise SPM contrast (p < 0.05 corrected) and an ANOVA performed on the mean percentage change in BOLD signa in the identified clusters of voxels (p < 0.006). These results show that activation of a region of the human orbitofrontal cortex is related to olfactory sensory-specific satiety. (C) 2000 Lippincott Williams and Wilkins.