The receptive surfaces for senses such as hearing (cochlea) and vision (retina) are organized along axes of sensory perception, but whether a similar type of organization is present in the olfactory epithelium is unknown. The authors measured the response of sensory receptors in the adult human olfactory epithelium to different odours. They found that the receptors that responded to pleasant odours tended to be grouped together in patches, as were the receptors that responded to unpleasant odours. These results suggest that like the cochlea and retina, the olfactory epithelium is organized along its primary axis of perception.