The human brain's ability to adapt to environmental changes is obvious in specific sensory domains of experts, and olfaction is one of the least investigated senses. As we have previously demonstrated that olfactory expertise is related to functional brain modifications, we investigated here whether olfactory expertise is also coupled with structural changes. We used voxel-based morphometry to compare the gray-matter volume in student and professional perfumers, as well as untrained control subjects, and accounted for all methodological improvements that have been recently developed to limit possible errors associated with image processing. In all perfumers, we detected an increase in gray-matter volume in the bilateral gyrus rectus/medial orbital gyrus (GR/MOG), an orbitofrontal area that surrounds the olfactory sulcus. In addition, gray-matter volume in the anterior PC and left GR/MOG was positively correlated with experience in professional perfumers. We concluded that the acute olfactory knowledge acquired through extensive olfactory training leads to the structural reorganization of olfactory brain areas.