Superior intellectual endowment had an adverse effect on the psychological development of several patients. In childhood, they regarded themselves as "exceptions" and they were so regarded by their environment. Precocious intelligence gave them access to information and understanding beyond their chronological age. The impact of their insights overwhelmed their immature egos, thus releasing libidinal and aggressive fantasies. This imposed further burdens on their developing egos. In the patients studied, the functioning of their intelligence was constricted. The greater sensitivity to stimuli required stronger methods to master the resultant excitation. It is suggested that for some patients markedly superior intelligence facilitates traumatic experiences which then lead to a neurosis.