This study investigated odor-category organization in three cultures by evaluating (i) the relationship between linguistic and perceptual categorization and (ii) the existence of an internal structure of odor categories. In the first experiment, three groups of 30 participants from American, French and Vietnamese cultures performed a sorting task. The first group sorted 40 odorants on the basis of odor similarity, the second group sorted 40 odor names on the basis of name similarity and the last group sorted 40 odor names on the basis of imagined odor similarity. Results showed that odor categorization was based on perceptual or conceptual similarity and was in part independent of word and imagined categorizations. In the second experiment, another group of 30 participants from each culture rated the typicality of the odorants for 11 odor categories. Results showed that some odorants were rated as more typical than others. Moreover, the typicality gradient predicted the odor space obtained in the odor sorting task in a consensual way among the three cultures. These results suggest that, as for other categories, odor categories are based on perceptual similarities rather than on semantic cues. Moreover odor-category structure might have a core representation which might be common to different cultures with boundaries which might be more culturally dependent.