A three-and-a-half-year-old boy developed an anxiety which was traced through the following stages: (1) A jealous and angry desire to bite in relation to his mother's pregnancy and his father's penis; (2) an obsessive interest in and fear of cutting instruments; (3) concern over his sister's lack of a penis; (4) a focussing of castration anxiety around his father's penis and a transformation of this into a fear of a wolf, or a hairy, biting animal. Spontaneous play and certain revealing experiences with his parents brought resolution of this specific fear, but a year and a half later new evidences of anxiety indicated that childhood fears must be allayed not once only but over and over again as they arise in many and varied forms.