From the point of view of the ancient medicine, apprehension, which is a feeling of fear and uncertainty regarding the probable outcome or consequences of something, significantly tormented the soul rather than the human body. Altogether with anger, hatred, and yearning, it was classified into the serious diseases, called by the physicians "perturbations of spirit" (perturbationes animi). The regimina sanitatis genre provided all the information about them. In this article, we presented a type of the apprehension which today we would term a phobia and describe it as a neurotic disorder. Firstly, we concentrated on the place of the apprehension amongst the other sicknesses of the soul. Secondly, we investigated two kinds of fear, its sources, and its peculiar symptoms. Finally, we depicted a few cases of phobia (musophobia, ailurophobia, hydrophobia, batophobia, etc.) rarely mentioned in the sixteenth-and seventeenth-century medical discourses.