The article analyses phenomenon of «smell of fear», data on toribons (pheromones of anxiety) secretion in insects and rats is provided. The studies which prove the existence of similar substances in frightened people vapor are described. Associative experiments data is cited: for majority of people fear is associated with a sour smell. The article describes an experiment conducted on dogs who were exposed to acetic acid smell with a rose smell as a control. Analysis of variance shows statistically significant increase of animals' behavioral reactions of fear under the influence of acetic acid smell. An interpretation of these findings is given in the framework of multimodal theories of emotions. It is suggested that evoking of fear reactions by sour smell is realized on the lower instinctive level, whereas higher level of emotion generation depends on learning and on individual experience of an animal.