How we smell is important to a lot of people, as indicated by the high spending on perfumes. Most perfumes are categorized as feminine or masculine, and this gender categorization is an important factor when people purchase perfumes. This thesis explores odor perception and perfume preference when the person sniffing the perfume does not know the commercial gender categorization. Three psychophysical experiments were conducted, in which the participants scaled the femininity and masculinity of the perfumes, indicated preferences, and gender categorized the perfumes. The perfumes were presented both in glass bottles and when applied on human skin. Results of three experiments indicate that female and male participants (20–30 years old) preferred the same perfumes, both for themselves and for their potential partners. The preferred perfumes tended to be “unisex,” that is, perceived as neither strongly feminine nor strongly masculine. The participants did not succeed well in identifying the commercial gender categorizations of the perfumes, and they did not succeed in guessing the gender of the human when the perfumes were applied on human skin. The commercial gender associations of the perfumes only corresponded to how they were perceived in the case of extremely feminine or extremely masculine perfumes. I conclude that the gender categorizations of most perfumes are not related to how they are actually perceived. / <p>At the time of the doctoral defence the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p>