The Olfactory Test is a sensory assay used to measure the olfactory ability, degree of social interest, and perception of social novelty in rodent models of CNS disorders. The nonsocial olfactory test employs water and synthetic odorants, while the social olfactory test uses water and urine samples from other animals. Cotton swabs dipped in odorant solution are placed in centrifuge tubes with holes drilled around the base at regular intervals, thus preventing the animal from chewing or sitting on the cotton swab. The centrifuge tube is taped down at one end of the empty cage; the subject is introduced at the opposite end. Subjects are exposed multiple times to three different odorants in a clean cage free of bedding. Trials are videotaped and later scored for the amount of time spent sniffing the odorant, defined as nose contact with the centrifuge tube. Sitting on, licking, or chewing the centrifuge tube is not counted. This olfactory test is useful for phenotyping transgenic strains of mice and evaluating the effect of novel chemical entities on olfactory sensation and discrimination.