Temporal and topographic regression are fundamental concepts in psychoanalytic psychopathology. Since hypnosis may be viewed as experimental regression, it may be possible to determine whether clinical regression is ever likely to be temporal in nature. The author evaluated the extensive literature on hypnosis from this point of view. For the sake of clarity, formal regression was omitted from consideration. Out of twenty-four empirical studies, twenty found evidence of the existence of topographic regression, while only a single study documented temporal regression. One may therefore state, with statistically based confidence, that hypnosis can evoke topographic regression and that it cannot produce temporal regression. That is, hypnotic subjects may think and act in childlike ways, but their behavior is not identical to that of a child. This finding raises the question of whether psychological regression is ever truly temporal. The experimental literature suggests that adult psychopathology does not involve the concrete reinstatement of infantile modes of cognition and experience.